Finally make prepareInstruction clone instrs + labels and not share any state with IRScope.

Problematic that we re-store info back into CFG at this point so debug output matches that
interpreter.  That is ok though since JIT should still be fine with these changes.  It is
not fine if we have debug on and interp is printing out CFG while the JIT is changing the
CFG.  A problem for another day.

Disabled OptimizeDynamicScope for now.  Something with cloning instrs + some closures
makes it break.  It appears not not find lvars in its flattened state.
Fix OptimizeDynScopesPass issue from last commit.  We were using a null check to initialize
which is no longer possible with new InterpreterContext.
Remove no longer correctly named preMethodFrameAndClass since we no longer have class
Remove some params for long dead rubyClass field on TC
Merge branch 'master' into truffle-head
[Truffle] Use BranchProfile factory method.