Re-land: Ensure that ArrayBuffers actively being used by the Web Audio API cannot be neutered

Source/wtf/ArrayBufferContents.cpp

Index: Source/wtf/ArrayBufferContents.cpp
diff --git a/Source/wtf/ArrayBufferContents.cpp b/Source/wtf/ArrayBufferContents.cpp
index f6c0c0a76c068b8907f54f41926615fc53555b5d..f62734bf8d5613b43965da9569c91c2f088f751c 100644
--- a/Source/wtf/ArrayBufferContents.cpp
+++ b/Source/wtf/ArrayBufferContents.cpp
@@ -28,6 +28,7 @@
 #include "wtf/ArrayBufferContents.h"
 
 #include "wtf/ArrayBufferDeallocationObserver.h"
+#include <string.h>
 
 namespace WTF {
 
@@ -97,6 +98,17 @@ void ArrayBufferContents::transfer(ArrayBufferContents& other)
     clear();
 }
 
+void ArrayBufferContents::copyTo(ArrayBufferContents& other)
+{
+    ASSERT(!other.m_sizeInBytes);
+    other.freeMemory(other.m_data);
+    allocateMemory(m_sizeInBytes, DontInitialize, other.m_data);
+    if (!other.m_data)
+        return;
+    memcpy(other.m_data, m_data, m_sizeInBytes);
+    other.m_sizeInBytes = m_sizeInBytes;
+}
+
 bool ArrayBufferContents::allocateMemory(size_t size, InitializationPolicy policy, void*& data)
 {
     if (policy == ZeroInitialize) {