Introduce FlexibleArrayBufferView and TypedFlexibleArrayBufferView

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 28 matching lines @@
 #define TOSTRING_VOID(type, var, value) \
     type var(value);                    \
     if (UNLIKELY(!var.prepare()))       \
         return;
 
 #define TOSTRING_DEFAULT(type, var, value, retVal) \
     type var(value);                               \
     if (UNLIKELY(!var.prepare()))                  \
         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)
+
 template <typename T>
 inline bool v8Call(v8::Maybe<T> maybe, T& outVariable)
 {
     if (maybe.IsNothing())
         return false;
     outVariable = maybe.FromJust();
     return true;
 }
 
 inline bool v8CallBoolean(v8::Maybe<bool> maybe)
@@ skipping 32 matching lines @@
 
 // The last "else" is to avoid dangling else problem.
 #define V8_CALL(outVariable, handle, methodCall, failureExpression)                \
     if (handle.IsEmpty() || !v8Call(handle->methodCall, outVariable)) { \
         failureExpression;                                                         \
     } else
 
 } // namespace blink
 
 #endif // V8BindingMacros_h