Add VS Debug Visualizer for layout and font classes
Add VS Debug Visualizer for layout and font classes

This patch adds major layout and font classes to Visual Studio Debug
Visualizer, specifically:
* LayoutObject shows its corresponding node.
* InlineBox, BidiRun, and LineLayoutItem shows its corresponding
  LayoutObject.
* TextRun shows its text.
* SimpleFontData and FontPlatformData shows family name and size.

R=yoichio@chromium.org, yosin@chromium.org, zturner@chromium.org

Review URL: https://codereview.chromium.org/1331793002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#348096}

CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend