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

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

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 36 matching lines @@
         return retVal;
 
 // Checks for a given v8::Value (value) whether it is an ArrayBufferView and
 // below a certain size limit. If below the limit, memory is allocated on the
 // stack to hold the actual payload. Keep the limit in sync with V8's
 // typed_array_max_size.
 #define allocateFlexibleArrayBufferViewStorage(value)                                       \
     (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;
 }
 
 inline bool v8CallBoolean(v8::Maybe<bool> maybe)
 {
     bool result;
     return v8Call(maybe, result) && result;
 }
 
 template <typename T>
 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>
 inline bool v8Call(v8::MaybeLocal<T> maybeLocal, v8::Local<T>& outVariable, v8::TryCatch& tryCatch)
 {
     bool success = maybeLocal.ToLocal(&outVariable);
     ASSERT(success || tryCatch.HasCaught());
+    if (!success)
+        emptyMaybeHandleReturned();
     return success;
 }
 
 template <typename T>
 inline T v8CallOrCrash(v8::Maybe<T> maybe)
 {
     return maybe.FromJust();
 }
 
 template <typename T>
 inline v8::Local<T> v8CallOrCrash(v8::MaybeLocal<T> maybeLocal)
 {
     return maybeLocal.ToLocalChecked();
 }
 
 #define V8_CALL(outVariable, handle, methodCall, failureExpression) \
     do { \
         if (handle.IsEmpty() || !v8Call(handle->methodCall, outVariable)) { \
             failureExpression; \
         } \
     } while (0)
 
 } // namespace blink
 
 #endif // V8BindingMacros_h