DevTools: Make TextEditor.tokenAtTextPosition() return exclusive end column

All call sites compensate for the inclusive end column by adding 1
to token.endColumn to get the actual token text.

R=lushnikov

Review URL: https://codereview.chromium.org/472793002

git-svn-id: svn://svn.chromium.org/blink/trunk@180260 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make variable names about |className| in PrivateScriptRunner more consistent

After this CL:

- |className| means a class name of a dependency interface (e.g., "Document").

- |scriptClassName| means a class name of the script (e.g., "DocumentXSLT").

BUG=341031

Review URL: https://codereview.chromium.org/473783003

git-svn-id: svn://svn.chromium.org/blink/trunk@180261 bbb929c8-8fbe-4397-9dbb-9b2b20218538