new file mode 100644
--- /dev/null
+++ b/dom/canvas/test/webgl-conf/cherry_picks.txt
@@ -0,0 +1,10 @@
+
+Cherries picked
+================================================================================
+Merge base
+
+commit e899c531173da8ba956df8de6dd74fb7d9b1fa9c
+Author: Patrick To <patrto@microsoft.com>
+Date:   Fri Mar 30 13:18:38 2018 -0700
+
+    Add unpack flip y test for depth textures (#2609)

--- a/dom/canvas/test/webgl-conf/import.py
+++ b/dom/canvas/test/webgl-conf/import.py
@@ -5,31 +5,33 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 assert __name__ == '__main__'
 
 from pathlib import *
 import subprocess
 import sys
 
+REL_PATH = '/dom/canvas/test/webgl-conf'
 REPO_DIR = Path.cwd()
 DIR_IN_GECKO = Path(__file__).parent
-assert not REPO_DIR.samefile(DIR_IN_GECKO), 'Run from the KhronosGroup/WebGL checkout.'
-assert DIR_IN_GECKO.as_posix().endswith('dom/canvas/test/webgl-conf')
+assert not REPO_DIR.samefile(DIR_IN_GECKO), 'Run this script from the source git checkout.'
+assert DIR_IN_GECKO.as_posix().endswith(REL_PATH) # Be paranoid with rm -rf.
 
-def print_now(*args):
-    print(*args)
-    sys.stdout.flush()
-
+gecko_base_dir = DIR_IN_GECKO.as_posix()[:-len(REL_PATH)]
+angle_dir = Path(gecko_base_dir, 'gfx/angle').as_posix()
+sys.path.append(angle_dir)
+from vendor_from_git import *
 
-def run_checked(*args, **kwargs):
-    print_now(' ', args)
-    return subprocess.run(args, check=True, shell=True, **kwargs)
+# --
 
+merge_base_from = sys.argv[1]
+record_cherry_picks(DIR_IN_GECKO, merge_base_from)
+
+# --
 
 src_dir = Path(REPO_DIR, 'sdk/tests').as_posix()
 dest_dir = Path(DIR_IN_GECKO, 'checkout').as_posix()
-assert dest_dir.endswith('dom/canvas/test/webgl-conf/checkout') # Be paranoid with rm -rf.
-run_checked("rm -rf '{}'".format(dest_dir))
-run_checked("mkdir '{}'".format(dest_dir));
-run_checked("cp -rT '{}' '{}'".format(src_dir, dest_dir));
+run_checked("rm -rI '{}'".format(dest_dir), shell=True)
+run_checked("mkdir '{}'".format(dest_dir), shell=True);
+run_checked("cp -rT '{}' '{}'".format(src_dir, dest_dir), shell=True);
 
 print_now('Done!')

new file mode 100644
--- /dev/null
+++ b/gfx/angle/vendor_from_git.py
@@ -0,0 +1,48 @@
+#! /usr/bin/env python3
+assert __name__ != '__main__'
+
+'''
+Any time we vendor[1] from an external git repo, we want to keep a record of the csets
+we're pulling from.
+
+This script leaves a record of the merge-base reference tip and cherry-picks that we pull
+into Gecko. (such as gfx/angle/cherry_picks.txt)
+'''
+
+from pathlib import *
+import subprocess
+import sys
+
+# --
+
+def print_now(*args):
+    print(*args)
+    sys.stdout.flush()
+
+
+def run_checked(*args, **kwargs):
+    print_now(' ', args)
+    return subprocess.run(args, check=True, **kwargs)
+
+# --
+
+def record_cherry_picks(dir_in_gecko, merge_base_from):
+    assert '/' in merge_base_from, 'Please specify a reference tip from a remote.'
+    log_path = Path(dir_in_gecko, 'cherry_picks.txt')
+    print_now('Logging cherry picks to {}.'.format(log_path))
+
+    print('cwd:', Path.cwd())
+    merge_base = run_checked('git', 'merge-base', 'HEAD', merge_base_from,
+                             stdout=subprocess.PIPE).stdout.decode().strip()
+
+    mb_info = run_checked('git', 'log', '{}~1..{}'.format(merge_base, merge_base),
+                          stdout=subprocess.PIPE).stdout
+    cherries = run_checked('git', 'log', merge_base + '..', stdout=subprocess.PIPE).stdout
+
+    with open(log_path, 'wb') as f:
+        f.write(cherries)
+        f.write(b'\nCherries picked')
+        f.write(b'\n' + (b'=' * 80))
+        f.write(b'\nMerge base')
+        f.write(b'\n\n')
+        f.write(mb_info)