OSR exit should have a direct reference to its target CodeBlock

[Geoffrey Garen]

From InlineCallFrame.h:

// FIXME: It's dangerous that OSR exit asks the Executable for a CodeBlock
// instead of having a pointer to a CodeBlock. If the GC discards a
// CodeBlock that we inline, then we will see a different CodeBlock
// at OSR time than we saw at compilation time. This works if compilation
// is mostly pure and the two CodeBlocks are equivalent, but that is a
// fragile thing to rely on.

inline CodeBlock* baselineCodeBlockForInlineCallFrame(InlineCallFrame* inlineCallFrame)
{
    RELEASE_ASSERT(inlineCallFrame);
    ScriptExecutable* executable = inlineCallFrame->executable.get();
    RELEASE_ASSERT(executable->structure()->classInfo() == FunctionExecutable::info());
    return static_cast<FunctionExecutable*>(executable)->baselineCodeBlockFor(inlineCallFrame->specializationKind());
}