Update GrRecordReplaceDraw to use SkTDynamicHash & add ReplaceDraw

Update GrRecordReplaceDraw to use SkTDynamicHash & add ReplaceDraw

Having hoisted layers from different pictures invalidates the assumptions of the old GrReplacements object. This is fixed by switching to a SkTDynamicHash-based back-end.

Sub-picture-layers also require that the replacement drawing occur for the sub-pictures too. The ReplaceDraw object is added to make this happen and limit the replacement lookup to saveLayer draw commands.

This is split out of (Fix sub-picture layer rendering bugs - https://codereview.chromium.org/597293002/).

BUG=skia:2315

Review URL: https://codereview.chromium.org/607763008