Improve ScriptForbiddenScope handling in cross-threaded code.

third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
index 2fc507ee53da36e187195431c465321e0dfb847f..f6b78def7b68cb344b85468fab7d9262030a01f7 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
@@ -281,9 +281,8 @@ void gcPrologueForMajorGC(v8::Isolate* isolate, bool constructRetainedObjectInfo
 
 void V8GCController::gcPrologue(v8::Isolate* isolate, v8::GCType type, v8::GCCallbackFlags flags)
 {
-    if (isMainThread()) {
+    if (isMainThread())
         ScriptForbiddenScope::enter();

[haraken, 2015/12/06 23:12:28]

Don't we want to use ScriptForbiddenIfMainThreadScope?

[sof, 2015/12/07 05:59:17]

Not able to a scope object, as the script re-enabling happens in gcEpilogue().

Having ScriptForbiddenIfMainThread::{enter,exit} static methods doesn't add
much, so I left them out.

-    }
 
     // TODO(haraken): It is not safe to run finalizers in a prologue callback
     // because V8AbstractEventListener's destructor cann call into V8. We