Rename bindingFoo to fooForBindings

Switch to the majority convention so that no one needs to investigate
which to use, as in https://codereview.chromium.org/141363002/

BUG=none

Review URL: https://codereview.chromium.org/141013010

git-svn-id: svn://svn.chromium.org/blink/trunk@165287 bbb929c8-8fbe-4397-9dbb-9b2b20218538