Set ArrayBufferContents size to 0 on allocation failure

Also, add a RELEASE_ASSERT when creating an ArrayBuffer from an
ArrayBufferContents that the backing store is non-NULL.

BUG=522128

Review URL: https://codereview.chromium.org/1302193002

git-svn-id: svn://svn.chromium.org/blink/trunk@200961 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/wtf/ArrayBuffer.h

@@ -122,6 +122,7 @@ PassRefPtr<ArrayBuffer> ArrayBuffer::create(const void* source, unsigned byteLen
 
 PassRefPtr<ArrayBuffer> ArrayBuffer::create(ArrayBufferContents& contents)
 {
+    RELEASE_ASSERT(contents.data());
     return adoptRef(new ArrayBuffer(contents));
 }
 

third_party/WebKit/Source/wtf/ArrayBufferContents.cpp

@@ -134,7 +134,7 @@ void ArrayBufferContents::DataHolder::allocateNew(unsigned sizeInBytes, SharingT
     void* data = nullptr;
     allocateMemory(sizeInBytes, policy, data);
     m_data = data;
-    m_sizeInBytes = sizeInBytes;
+    m_sizeInBytes = data ? sizeInBytes : 0;
     m_isShared = isShared;
 }