Inline CursorChromium.cpp into Cursor.cpp.

No other platforms exist in Blink anymore.

Fix indentation in Cursor.h while here.

BUG=248003

Review URL: https://chromiumcodereview.appspot.com/16548005

git-svn-id: svn://svn.chromium.org/blink/trunk@152097 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove core/platform/KURL.h and core/platform/KURLHash.h.

These were forwarding headers for their counterparts in weborigin/ and
can now go away.

Adjust all inclusion sites accordingly and clean up includes along the
way.

BUG=247972

Review URL: https://chromiumcodereview.appspot.com/15904017

git-svn-id: svn://svn.chromium.org/blink/trunk@152098 bbb929c8-8fbe-4397-9dbb-9b2b20218538