- Remove flag to enable adjustable large cursor and make it enabled by
  default.

BUG=591493,700256,700260
TEST=Go to accessibility section of settings, and confirm that
     adjustable large cursor is enabled by default.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2814743009
Cr-Commit-Position: refs/heads/master@{#466271}