Check if ArrayBuffer allocation in ArrayBufferBuilder is successful.

Source/core/fileapi/FileReaderLoader.cpp

Index: Source/core/fileapi/FileReaderLoader.cpp
diff --git a/Source/core/fileapi/FileReaderLoader.cpp b/Source/core/fileapi/FileReaderLoader.cpp
index 617dca714e5b7db823d338419e7eeec0a6229ae0..74e518bcb39cfff9711272e55bbfcaecf3aa1a4d 100644
--- a/Source/core/fileapi/FileReaderLoader.cpp
+++ b/Source/core/fileapi/FileReaderLoader.cpp
@@ -201,18 +201,20 @@ void FileReaderLoader::didReceiveResponse(unsigned long, const ResourceResponse&
             return;
         }
 
-        if (initialBufferLength < 0) {
+        if (initialBufferLength < 0)
             m_rawData = adoptPtr(new ArrayBufferBuilder());
-        } else {
+        else
             m_rawData = adoptPtr(new ArrayBufferBuilder(static_cast<unsigned>(initialBufferLength)));
-            // Total size is known. Set m_rawData to ignore overflowed data.
-            m_rawData->setVariableCapacity(false);
-        }
 
-        if (!m_rawData) {
+        if (!m_rawData || !m_rawData->isValid()) {
             failed(FileError::NOT_READABLE_ERR);
             return;
         }
+
+        if (initialBufferLength >= 0) {
+            // Total size is known. Set m_rawData to ignore overflowed data.
+            m_rawData->setVariableCapacity(false);
+        }
     }
 
     if (m_client)