Fix build with gcc 4.8 and C++11 support enabled

Fix build with gcc 4.8 and C++11 support enabled. The build was failing because
of a naming conflict between CheckedState enum in wtf/CheckedArithmetic.h and
the CheckedState value in ThemeTypes.h's ControlState enum.

This CL renames ThemeTypes.h's ControlState enum values to end with
"ControlState" instead of "State" to reduce the risk of naming conflicts.

Review URL: https://codereview.chromium.org/289163003

git-svn-id: svn://svn.chromium.org/blink/trunk@174231 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Decrease call sites of GetCurrentContext

People tend to use a "current" context when they don't know what context they should use. This leads to cross-world leakage, so I'm verifying if those call sites are correct or not one by one. In the verification process, I'm decreasing the number of the call sites of GetCurrentContext.

This CL just replaces GetCurrentContext with other equivalent alternatives. This CL doesn't change any behavior.

BUG=357144

Review URL: https://codereview.chromium.org/287003009

git-svn-id: svn://svn.chromium.org/blink/trunk@174232 bbb929c8-8fbe-4397-9dbb-9b2b20218538