Make WebKitCSSMatrix an alias of DOMMatrix

third_party/WebKit/Source/core/frame/Window.idl

Index: third_party/WebKit/Source/core/frame/Window.idl
diff --git a/third_party/WebKit/Source/core/frame/Window.idl b/third_party/WebKit/Source/core/frame/Window.idl
index 2bbfaa865627a17625dfbc751ada0eb494480289..804a697cf203ef9d6025ba395c53559bd6c964c2 100644
--- a/third_party/WebKit/Source/core/frame/Window.idl
+++ b/third_party/WebKit/Source/core/frame/Window.idl
@@ -204,6 +204,8 @@
 
     // https://w3c.github.io/webappsec/specs/powerfulfeatures/#monkey-patching-global-object
     readonly attribute boolean isSecureContext;
+
+    readonly attribute DOMMatrixConstructor WebKitCSSMatrix;

[simonp, 2017/05/04 08:35:21]

This is different from what the spec requires. The spec says:
The difference is that a readonly attribute has a getter instead of being a
straight property. The attribute is also enumerable.

[foolip, 2017/05/04 14:43:25]

This affects all of our aliases, so that's probably something we'd want to fix
in our bindings generator somehow. Let's see how the tests fail first.

[zino, 2017/05/05 11:43:21]

FYI, I tried simonp@'s test in latest chromium with this patch.

** Test Result **
This is a testharness.js-based test.
PASS Equivalence test 
FAIL Property descriptor for WebKitCSSMatrix assert_true: writable expected true
got false
PASS Property descriptor for DOMMatrix 
Harness: the test ran to completion.

We probably should remove |readonly|?

 };
 
 // https://html.spec.whatwg.org/#transferable-objects