This is the first part to refactoring the JSNativeContextSpecialization
class, which has grown way too big recently.

Also don't collect cross context feedback for the CallIC in general.
Neither TurboFan nor Crankshaft can make any use of cross context
JSFunction feedback that is collected by the CallIC, so there's no
point in gathering that feedback at all (it just complicates the
checking that is necessary in the compilers). What we should do
instead at some point (when Crankshaft becomes less important) is
to collect the SharedFunctionInfo as feedback for those cases.

R=yangguo@chromium.org
BUG=v8:4470
LOG=n

Review URL: https://codereview.chromium.org/1451273002

Cr-Commit-Position: refs/heads/master@{#32022}