Revert 148297 "Introduce bindings.gyp"

This is a test rollout to see if it helps with the flaky compile
breakage we are seeing when generating IDLs:

Could NOT find IDL file for interface "InternalSettingsGenerated"!

> Introduce bindings.gyp
> 
> This CL moves the responsibility for building the bindings
> from WebCore.gyp to bindings.gyp. The bindings.gyp file
> contains a bunch of redundant declarations with WebCore.gyp.
> After this patch lands, the next step will be to refactor
> these declarations into a place where they can be shared.
> 
> BUG=230253
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=148156
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=148223
> 
> Review URL: https://codereview.chromium.org/14110002

TBR=abarth@chromium.org

Review URL: https://codereview.chromium.org/13998018

git-svn-id: svn://svn.chromium.org/blink/trunk@148381 bbb929c8-8fbe-4397-9dbb-9b2b20218538