The only barrier is the var stack.
Created attachment 35135 [details] The Patch
Sending JavaScriptCore/ChangeLog Sending JavaScriptCore/bytecode/CodeBlock.h Sending JavaScriptCore/bytecompiler/BytecodeGenerator.cpp Sending JavaScriptCore/interpreter/Interpreter.cpp Sending JavaScriptCore/parser/Nodes.h Sending JavaScriptCore/runtime/Executable.cpp Sending JavaScriptCore/runtime/Executable.h Transmitting file data ....... Committed revision 47519.