--- a/layout/reftests/mathml/font-inflation-1-ref.html
+++ b/layout/reftests/mathml/font-inflation-1-ref.html
@@ -23,31 +23,33 @@
   </mrow>
   </math>'
 should have the same size as inline math
 '<math>
     <mrow id="inline">
       <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
       <mo>+</mo>
     </mrow>
-  </math>', display math
-<math display="block">
-    <mrow id="display">
-      <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
-      <mo>+</mo>
-    </mrow>
-  </math>
+  </math>'
 or math in a table: '<math><mtable><mtr>
     <mtd>
       <mrow id="cell">
         <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
         <mo>+</mo>
       </mrow>
     </mtd>
   </mtr></mtable></math>'
+(but not necessarily the same size as block-level math
+<math display="block">
+    <mrow id="display">
+      <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
+      <mo>+</mo>
+    </mrow>
+  </math>
+because it forms a BFC and hence is its own inflation container.)
 Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
 tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
 quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
 consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
 cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
 proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem
 ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor
 incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis

--- a/layout/reftests/mathml/font-inflation-1.html
+++ b/layout/reftests/mathml/font-inflation-1.html
@@ -29,21 +29,19 @@
         }
       }
 
       function verifySizes() {
         /* Compare the size of the elements in the inline and display equations
            against the reference mtext elements. */
         var ref = document.getElementById("ref");
         var inline = document.getElementById("inline");
-        var display = document.getElementById("display");
         var cell = document.getElementById("cell");
         for (var i = 0; i < ref.children.length; i++) {
           verifySize(inline.children[i], ref.children[i]);
-          verifySize(display.children[i], ref.children[i]);
           verifySize(cell.children[i], ref.children[i]);
         }
 
         document.documentElement.removeAttribute("class");
       }
 
       window.addEventListener("MozReftestInvalidate", verifySizes);
     </script>
@@ -58,31 +56,33 @@
   </mrow>
   </math>'
 should have the same size as inline math
 '<math>
     <mrow id="inline">
       <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
       <mo>+</mo>
     </mrow>
-  </math>', display math
-<math display="block">
-    <mrow id="display">
-      <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
-      <mo>+</mo>
-    </mrow>
-  </math>
+  </math>'
 or math in a table: '<math><mtable><mtr>
     <mtd>
       <mrow id="cell">
         <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
         <mo>+</mo>
       </mrow>
     </mtd>
   </mtr></mtable></math>'
+(but not necessarily the same size as block-level math
+<math display="block">
+    <mrow id="display">
+      <mtext style="font-family: dtls-1" mathvariant="fraktur">a</mtext>
+      <mo>+</mo>
+    </mrow>
+  </math>
+because it forms a BFC and hence is its own inflation container.)
 Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
 tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
 quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
 consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
 cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
 proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem
 ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor
 incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis