Catch uncaught promise rejections from V8 and log to console.

Source/bindings/core/v8/ScriptValue.h

Index: Source/bindings/core/v8/ScriptValue.h
diff --git a/Source/bindings/core/v8/ScriptValue.h b/Source/bindings/core/v8/ScriptValue.h
index d326c402d31161444ee3fac68ea8d13fdf001ede..cf8b441edd52abd20bad1964c1628368c62c6409 100644
--- a/Source/bindings/core/v8/ScriptValue.h
+++ b/Source/bindings/core/v8/ScriptValue.h
@@ -135,12 +135,18 @@ public:
         m_value = nullptr;
     }
 
+    int identityHash() const;
+
     v8::Handle<v8::Value> v8Value() const;
     v8::Handle<v8::Value> v8ValueUnsafe() const;
 
     bool toString(String&) const;
     PassRefPtr<JSONValue> toJSONValue(ScriptState*) const;
 
+    // Hash table deleted values, which are only constructed and never copied or destroyed.
+    ScriptValue(WTF::HashTableDeletedValueType) : m_scriptState(WTF::HashTableDeletedValue) { }

[yurys, 2014/10/03 15:08:05]

If we init m_value with WTF::HashTableDeletedValue instead it would simplify
isEmptyValue in ScriptValueHashTraits below.

[aandrey, 2014/10/06 10:52:56]

m_value->isEmpty(); will deref (-1) pointer

+    bool isHashTableDeletedValue() const { return m_scriptState.isHashTableDeletedValue(); }
+
 private:
     RefPtr<ScriptState> m_scriptState;
     RefPtr<SharedPersistent<v8::Value> > m_value;