Add IMMEDIATE_CRASH to measure how much V8 APIs return empty MaybeLocal handles

third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.cpp b/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..29c42a0d55b4702c94167c4e8754733d5a804356
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.cpp
@@ -0,0 +1,16 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "wtf/Assertions.h"
+
+namespace blink {
+
+// TODO(haraken): This function was added to investigate how much V8 APIs
+// return empty MaybeLocal handles. Remove this once we finish fixing crbug.com/625512.
+NEVER_INLINE void emptyMaybeHandleReturned()
+{
+    IMMEDIATE_CRASH();
+}
+
+} // namespace blink