The JSFrameSpecialization specializes an OSR graph to the current
unoptimized frame on which we will perform the on-stack replacement.
This is used for asm.js functions, where we cannot reuse the OSR code
object anyway because of context specialization, and so we could as well
specialize to the max instead.

It works by replacing all OsrValues in the graph with their values in
the JavaScriptFrame.

The idea is that using this trick we get better performance without
doing the unsound backpropagation of types to OsrValues later. This is
the first step towards fixing OSR for TurboFan.

R=jarin@chromium.org
BUG=v8:4273
LOG=n

Review URL: https://codereview.chromium.org/1225683004

Cr-Commit-Position: refs/heads/master@{#29476}