[turbofan] Move context specialization into JSContextSpecializer.

[turbofan] Move context specialization into JSContextSpecializer.

Remove the context specialization hack from the AstGraphBuilder, and
properly specialize to the function context in the JSContextSpecializer.
And replace the correct context in the JSInliner.

R=bmeurer@chromium.org,danno@chromium.org,titzer@chromium.org

[Michael Starzinger, 2015-07-02 13:49:37]

mstarzinger@chromium.org changed reviewers:
+ danno@chromium.org, titzer@chromium.org

[titzer, 2015-07-03 09:28:17]

https://codereview.chromium.org/1221103003/diff/20001/src/compiler/ast-graph-...
File src/compiler/ast-graph-builder.cc (right):

https://codereview.chromium.org/1221103003/diff/20001/src/compiler/ast-graph-...
src/compiler/ast-graph-builder.cc:4081: // TODO(titzer): use a real OSR value
here; a parameter works by accident.
To get rid of this TODO, we need a special OSR value that will represent the
context on the stack that the linkage knows about. Then context specialization
won't be confused by seeing a weird parameter that really represents an OSR
value.

We should do this in a separate CL first.

[Michael Starzinger, 2015-07-06 13:08:40]

Closing, superseded by: https://codereview.chromium.org/1218873005/

https://codereview.chromium.org/1221103003/diff/20001/src/compiler/ast-graph-...
File src/compiler/ast-graph-builder.cc (right):

https://codereview.chromium.org/1221103003/diff/20001/src/compiler/ast-graph-...
src/compiler/ast-graph-builder.cc:4081: // TODO(titzer): use a real OSR value
here; a parameter works by accident.
On 2015/07/03 09:28:17, titzer wrote:
> To get rid of this TODO, we need a special OSR value that will represent the
> context on the stack that the linkage knows about. Then context specialization
> won't be confused by seeing a weird parameter that really represents an OSR
> value.
> 
> We should do this in a separate CL first.

Done, see: https://codereview.chromium.org/1213043005/