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

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

Index: third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h b/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
index 6f84252260e02cd6de62abffa92ec447a3b66562..583266b7225600ba8c74f3a20179b1706d4e13cf 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8BindingMacros.h
@@ -54,11 +54,15 @@ namespace blink {
     (value->IsArrayBufferView() && (value.As<v8::ArrayBufferView>()->ByteLength() <= 64) ?  \
         alloca(value.As<v8::ArrayBufferView>()->ByteLength()) : nullptr)
 
+void emptyMaybeHandleReturned();
+
 template <typename T>
 inline bool v8Call(v8::Maybe<T> maybe, T& outVariable)
 {
-    if (maybe.IsNothing())
+    if (maybe.IsNothing()) {
+        emptyMaybeHandleReturned();
         return false;
+    }
     outVariable = maybe.FromJust();
     return true;
 }
@@ -74,13 +78,18 @@ inline bool v8Call(v8::Maybe<T> maybe, T& outVariable, v8::TryCatch& tryCatch)
 {
     bool success = v8Call(maybe, outVariable);
     ASSERT(success || tryCatch.HasCaught());
+    if (!success)
+        emptyMaybeHandleReturned();
     return success;
 }
 
 template <typename T>
 inline bool v8Call(v8::MaybeLocal<T> maybeLocal, v8::Local<T>& outVariable)
 {
-    return maybeLocal.ToLocal(&outVariable);
+    bool success = maybeLocal.ToLocal(&outVariable);
+    if (!success)
+        emptyMaybeHandleReturned();
+    return success;
 }
 
 template <typename T>
@@ -88,6 +97,8 @@ inline bool v8Call(v8::MaybeLocal<T> maybeLocal, v8::Local<T>& outVariable, v8::
 {
     bool success = maybeLocal.ToLocal(&outVariable);
     ASSERT(success || tryCatch.HasCaught());
+    if (!success)
+        emptyMaybeHandleReturned();
     return success;
 }