evaluateScriptInMainWorld() should check if the target context exists before evaluating a script

Source/bindings/core/v8/ScriptController.cpp

Index: Source/bindings/core/v8/ScriptController.cpp
diff --git a/Source/bindings/core/v8/ScriptController.cpp b/Source/bindings/core/v8/ScriptController.cpp
index b96443c89dc34cd3cd32e14db2ccd1d4354a1646..a7b2b1c84f729500b619f731fd3250ae2ece934f 100644
--- a/Source/bindings/core/v8/ScriptController.cpp
+++ b/Source/bindings/core/v8/ScriptController.cpp
@@ -583,11 +583,12 @@ v8::Local<v8::Value> ScriptController::evaluateScriptInMainWorld(const ScriptSou
     const String* savedSourceURL = m_sourceURL;
     m_sourceURL = &sourceURL;
 
-    ScriptState* scriptState = ScriptState::forMainWorld(m_frame);
-    if (scriptState->contextIsEmpty())
+    v8::EscapableHandleScope handleScope(m_isolate);
+    v8::Handle<v8::Context> context = toV8Context(m_frame, DOMWrapperWorld::mainWorld());
+    if (context.IsEmpty())
         return v8::Local<v8::Value>();
 
-    v8::EscapableHandleScope handleScope(scriptState->isolate());
+    ScriptState* scriptState = ScriptState::from(context);
     ScriptState::Scope scope(scriptState);
 
     RefPtr<LocalFrame> protect(m_frame);