Add access checks to V8WrapperInstationScope.

Source/bindings/core/v8/V8DOMWrapper.h

Index: Source/bindings/core/v8/V8DOMWrapper.h
diff --git a/Source/bindings/core/v8/V8DOMWrapper.h b/Source/bindings/core/v8/V8DOMWrapper.h
index dbe68a1b08316e3db33ceddd845530c2240cfbf1..5dbad6421e53b62438ee54db2596748a48f742a9 100644
--- a/Source/bindings/core/v8/V8DOMWrapper.h
+++ b/Source/bindings/core/v8/V8DOMWrapper.h
@@ -31,8 +31,10 @@
 #ifndef V8DOMWrapper_h
 #define V8DOMWrapper_h
 
+#include "bindings/core/v8/BindingSecurity.h"
 #include "bindings/core/v8/DOMDataStore.h"
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/V8Binding.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RawPtr.h"
 #include "wtf/text/AtomicString.h"
@@ -106,7 +108,7 @@ inline v8::Local<v8::Object> V8DOMWrapper::associateObjectWithWrapper(v8::Isolat
 
 class V8WrapperInstantiationScope {
 public:
-    V8WrapperInstantiationScope(v8::Local<v8::Object> creationContext, v8::Isolate* isolate)
+    V8WrapperInstantiationScope(v8::Local<v8::Object> creationContext, v8::Isolate* isolate, bool withSecurityCheck = true)

[Yuki, 2015/07/30 11:00:54]

The style guide recommends an enum value.
https://www.chromium.org/blink/coding-style#TOC-Names
See 10th rule.

         : m_didEnterContext(false)
         , m_context(isolate->GetCurrentContext())
     {
@@ -119,6 +121,14 @@ public:
         // is different from the context that we are about to enter.
         if (contextForWrapper == m_context)
             return;
+        if (withSecurityCheck) {

[haraken, 2015/07/30 10:43:36]

Would you help me understand why we want to enable the check only for Location?
Given that this is a slow path, I guess it would be better to enable the
security check for all objects.

+            // If the context is different, we need to make sure that the current
+            // context has access to the creation context.
+            if (!m_context.IsEmpty()) {

[haraken, 2015/07/30 10:43:36]

m_context shouldn't be empty here.

+                Frame* frame = toFrameIfNotDetached(contextForWrapper);
+                RELEASE_ASSERT(!frame || BindingSecurity::shouldAllowAccessToFrame(isolate, frame, DoNotReportSecurityError));

[haraken, 2015/07/30 10:43:36]

Just to confirm: This will allow a wrapper creation on a cross-origin frame that
is already detached, but is it an expected behavior?

c.f., shouldAllowAccessToFrame() returns false for a null frame.

+            }
+        }
         m_context = v8::Local<v8::Context>::New(isolate, contextForWrapper);
         m_didEnterContext = true;
         m_context->Enter();