Make GeometryMapperOption enum class

Enumerator kUseGeometryMapper defined both in
src/third_party/blink/renderer/core/paint/paint_layer.h and
src/third_party/blink/renderer/core/layout/layout_object.h files which
causes a -Wshadow warning when both of these files are included

Bug: None
Change-Id: Iaabfb627c656d9a54db9a4f8249034696aa8dbbb
Reviewed-on: https://chromium-review.googlesource.com/c/1384284
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618262}
6 files changed