--- a/devtools/client/inspector/markup/test/browser_markup_events3.js
+++ b/devtools/client/inspector/markup/test/browser_markup_events3.js
@@ -13,98 +13,98 @@ const TEST_URL = URL_ROOT + "doc_markup_
 loadHelperScript("helper_events_test_runner.js");
 
 const TEST_DATA = [ // eslint-disable-line
   {
     selector: "#es6-method",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":91",
+        filename: TEST_URL + ":97",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "es6Method() {\n" +
                  "  alert(\"obj.es6Method\");\n" +
                  "}"
       }
     ]
   },
   {
     selector: "#generator",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":96",
+        filename: TEST_URL + ":102",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "function* generator() {\n" +
                  "  alert(\"generator\");\n" +
                  "}"
       }
     ]
   },
   {
     selector: "#anon-generator",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":55",
+        filename: TEST_URL + ":56",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "function*() {\n" +
                  "  alert(\"anonGenerator\");\n" +
                  "}"
       }
     ]
   },
   {
     selector: "#named-function-expression",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":23",
+        filename: TEST_URL + ":24",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "let namedFunctionExpression =\n" +
                  "  function foo() {\n" +
                  "    alert(\"namedFunctionExpression\");\n" +
                  "  }"
       }
     ]
   },
   {
     selector: "#anon-function-expression",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":27",
+        filename: TEST_URL + ":28",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "let anonFunctionExpression = function() {\n" +
                  "  alert(\"anonFunctionExpression\");\n" +
                  "}"
       }
     ]
   },
   {
     selector: "#returned-function",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":32",
+        filename: TEST_URL + ":33",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "function bar() {\n" +
                  "  alert(\"returnedFunction\");\n" +
                  "}"
       }
@@ -138,24 +138,40 @@ const TEST_DATA = [ // eslint-disable-li
       }
     ]
   },
   {
     selector: "#multiple-assignment",
     expected: [
       {
         type: "click",
-        filename: TEST_URL + ":42",
+        filename: TEST_URL + ":43",
         attributes: [
           "Bubbling",
           "DOM2"
         ],
         handler: "let multipleAssignment = foo = bar = function multi() {\n" +
                  "  alert(\"multipleAssignment\");\n" +
                  "}"
       }
     ]
   },
+  {
+    selector: "#promise",
+    expected: [
+      {
+        type: "click",
+        filename: ":0",
+        attributes: [
+          "Bubbling",
+          "DOM2"
+        ],
+        handler: "function() {\n" +
+                 "  [native code]\n" +
+                 "}"
+      }
+    ]
+  },
 ];
 
 add_task(function* () {
   yield runEventPopupTests(TEST_URL, TEST_DATA);
 });

--- a/devtools/client/inspector/markup/test/doc_markup_events3.html
+++ b/devtools/client/inspector/markup/test/doc_markup_events3.html
@@ -6,17 +6,18 @@
     #es6-method,
     #generator,
     #anon-generator,
     #named-function-expression,
     #anon-function-expression,
     #returned-function,
     #constructed-function,
     #constructed-function-with-body-string,
-    #multiple-assignment {
+    #multiple-assignment,
+    #promise {
       border: 1px solid #000;
       width: 200px;
       min-height: 1em;
       cursor: pointer;
     }
     </style>
     <script type="application/javascript;version=1.8">
       let namedFunctionExpression =
@@ -76,16 +77,21 @@
         let constructedFunctionWithBodyStringNode =
           document.getElementById("constructed-function-with-body-string");
         constructedFunctionWithBodyStringNode
           .addEventListener("click", constructedFuncWithBodyString);
 
         let multipleAssignmentNode =
           document.getElementById("multiple-assignment");
         multipleAssignmentNode.addEventListener("click", multipleAssignment);
+
+        let promiseNode = document.getElementById("promise");
+        new Promise((resolve, reject) => {
+          promiseNode.addEventListener("click", resolve);
+        });
       }
 
       function handleEventClick(hehe) {
 
       }
 
       handleEventClick.prototype = {
         es6Method() {
@@ -106,10 +112,11 @@
     <div id="named-function-expression">Named Function Expression</div>
     <div id="anon-function-expression">Anonymous Function Expression</div>
     <div id="returned-function">Returned Function</div>
     <div id="constructed-function">Constructed Function</div>
     <div id="constructed-function-with-body-string">
       Constructed Function with body string
     </div>
     <div id="multiple-assignment">Multiple Assignment</div>
+    <div id="promise">Promise</div>
   </body>
 </html>

--- a/devtools/client/themes/inspector.css
+++ b/devtools/client/themes/inspector.css
@@ -34,16 +34,17 @@
 #inspector-element-add-button {
   list-style-image: url("chrome://devtools/skin/images/add.svg");
 }
 
 /* Tooltip: Events */
 
 #devtools-tooltip-events-container {
   margin: -4px; /* Compensate for the .panel-arrowcontent padding. */
+  min-width: 390px;
   max-width: 590px;
   overflow-y: auto;
 }
 
 .event-header {
   display: flex;
   align-items: center;
   cursor: pointer;

--- a/devtools/server/actors/inspector.js
+++ b/devtools/server/actors/inspector.js
@@ -555,58 +555,66 @@ var NodeActor = exports.NodeActor = prot
       }
     }
 
     if (listenerDO.isBoundFunction) {
       listenerDO = listenerDO.boundTargetFunction;
     }
 
     let script = listenerDO.script;
-    let scriptSource = script.source.text;
-    let functionSource =
-      scriptSource.substr(script.sourceStart, script.sourceLength);
-
-    /*
-    The script returned is the whole script and
-    scriptSource.substr(script.sourceStart, script.sourceLength) returns
-    something like this:
-      () { doSomething(); }
-
-    So we need to use some regex magic to get the appropriate function info
-    e.g.:
-      () => { ... }
-      function doit() { ... }
-      doit: function() { ... }
-      es6func() { ... }
-      var|let|const foo = function () { ... }
-      function generator*() { ... }
-    */
-    let scriptBeforeFunc = scriptSource.substr(0, script.sourceStart);
-    let matches = scriptBeforeFunc.match(RX_FUNC_NAME);
-    if (matches && matches.length > 0) {
-      functionSource = matches[0].trim() + functionSource;
+
+    let functionSource;
+    if (script) {
+      let scriptSource = script.source.text;
+      functionSource =
+        scriptSource.substr(script.sourceStart, script.sourceLength);
+
+     /*
+      The script returned is the whole script and
+      scriptSource.substr(script.sourceStart, script.sourceLength) returns
+      something like this:
+        () { doSomething(); }
+
+      So we need to use some regex magic to get the appropriate function info
+      e.g.:
+        () => { ... }
+        function doit() { ... }
+        doit: function() { ... }
+        es6func() { ... }
+        var|let|const foo = function () { ... }
+        function generator*() { ... }
+      */
+      let scriptBeforeFunc = scriptSource.substr(0, script.sourceStart);
+      let matches = scriptBeforeFunc.match(RX_FUNC_NAME);
+      if (matches && matches.length > 0) {
+        functionSource = matches[0].trim() + functionSource;
+      }
+    } else {
+      functionSource = handler.toString();
     }
 
     let dom0 = false;
 
     if (typeof node.hasAttribute !== "undefined") {
       dom0 = !!node.hasAttribute("on" + type);
     } else {
       dom0 = !!node["on" + type];
     }
 
-    let line = script.startLine;
-    let url = script.url;
+    let line = script ? script.startLine : 0;
+    let url = script ? script.url : "";
     let origin = url + (dom0 ? "" : ":" + line);
     let searchString;
 
     if (dom0) {
-      searchString = "on" + type + "=\"" + script.source.text + "\"";
-    } else {
-      scriptSource = "    " + scriptSource;
+      if (script) {
+        searchString = "on" + type + "=\"" + script.source.text + "\"";
+      } else {
+        searchString = "on" + type + "=\"" + functionSource + "\"";
+      }
     }
 
     let eventObj = {
       type: typeof override.type !== "undefined" ? override.type : type,
       handler: functionSource.trim(),
       origin: typeof override.origin !== "undefined" ?
                      override.origin : origin,
       searchString: typeof override.searchString !== "undefined" ?