bindings: Add a macro for V8 Maybe<T> APIs.

Source/bindings/core/v8/V8BindingMacros.h

Index: Source/bindings/core/v8/V8BindingMacros.h
diff --git a/Source/bindings/core/v8/V8BindingMacros.h b/Source/bindings/core/v8/V8BindingMacros.h
index 77a7faafd9a59fd952e4ad244a637f205fda3013..780b8715d0f795bbf3dd3149f4f8c3a754c7c99f 100644
--- a/Source/bindings/core/v8/V8BindingMacros.h
+++ b/Source/bindings/core/v8/V8BindingMacros.h
@@ -77,6 +77,22 @@ namespace blink {
     if (UNLIKELY(!var.prepare()))                  \
         return retVal;
 
+template <typename T>
+bool inline getValueFromMaybe(v8::Maybe<T> maybe, T& outVariable)
+{
+    if (maybe.IsNothing())
+        return false;
+    outVariable = maybe.FromJust();
+    return true;
+}
+
+#define V8_CALL(outVariable, handle, methodCall, failureExpression)                \
+    if (handle.IsEmpty() || !getValueFromMaybe(handle->methodCall, outVariable)) { \

[Jens Widell, 2015/03/11 07:18:22]

Wrap the whole macro body in a do{}while()? Defined like this,

  if (<condition>)
    V8_CALL(...);
  else
    <fallback>;

does not do what one expects.

[bashi, 2015/03/11 07:33:43]

Done.

+        do {                                                                       \
+            failureExpression;                                                     \
+        } while (false);                                                           \
+    }
+
 } // namespace blink
 
 #endif // V8BindingMacros_h