Expose FontFaceSetLoadEvent and add a constructor for it

third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h

Index: third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h b/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
index d9cd41637c832b5da4f7e9f4e01f101279a1370d..d605d2b0c6f88846eebe786372d540417e7d6275 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
@@ -21,19 +21,20 @@ class ScriptState;
 class ScriptWrappable;
 
 // Apply |X| for each pair of (InterfaceName, PrivateKeyName).
-#define V8_PRIVATE_PROPERTY_FOR_EACH(X) \
-  X(CustomEvent, Detail)                \
-  X(DOMException, Error)                \
-  X(ErrorEvent, Error)                  \
-  X(IDBObserver, Callback)              \
-  X(IntersectionObserver, Callback)     \
-  X(MessageEvent, CachedData)           \
-  X(MutationObserver, Callback)         \
-  X(PerformanceObserver, Callback)      \
-  X(SameObject, NotificationActions)    \
-  X(SameObject, NotificationData)       \
-  X(SameObject, NotificationVibrate)    \
-  X(V8NodeFilterCondition, Filter)      \
+#define V8_PRIVATE_PROPERTY_FOR_EACH(X)        \
+  X(CustomEvent, Detail)                       \
+  X(DOMException, Error)                       \
+  X(ErrorEvent, Error)                         \
+  X(IDBObserver, Callback)                     \
+  X(IntersectionObserver, Callback)            \
+  X(MessageEvent, CachedData)                  \
+  X(MutationObserver, Callback)                \
+  X(PerformanceObserver, Callback)             \
+  X(SameObject, FontFaceSetLoadEventFontfaces) \

[foolip, 2016/12/16 14:46:36]

I didn't know we had to do this for SaveSameObject. Can you blame and ask
whoever wrote the surrounding code if it's expected that this will grow by a lot
and if that's a problem?

[lunalu1, 2016/12/16 15:44:56]

If we don't do that, it simply won't compile. 

[foolip, 2016/12/16 16:13:07]

Right, I'm just wondering if there's any cost to introducing more of these, in
startup time or anything else. If the list can grow endlessly without problem,
then all is well.

+  X(SameObject, NotificationActions)           \
+  X(SameObject, NotificationData)              \
+  X(SameObject, NotificationVibrate)           \
+  X(V8NodeFilterCondition, Filter)             \
   X(Window, DocumentCachedAccessor)
 
 // The getter's name for a private property.