Simplify DMC::InvalidateRectsForAllMarkers()

Implement DocumentMarkerController::InvalidateRectsForAllMarkers() on top of
InvalidateRectsForMarkersInNode(). This makes the code easier to understand and
simplifies maintenance.

BUG=707867

Review-Url: https://codereview.chromium.org/2896483002
Cr-Commit-Position: refs/heads/master@{#473114}
1 file changed