https://bugs.webkit.org/show_bug.cgi?id=77480

Reviewed by Antti Koivisto.

Put tiles in a hash map keyed off the tile index.

* platform/graphics/ca/mac/TileCache.h:
Shuffle member variables around so the order makes more sense.
Add the tile map.

* platform/graphics/ca/mac/TileCache.mm:
(WebCore::TileCache::TileCache):
Update member initializers.

(WebCore::TileCache::setNeedsDisplayInRect):
Call tileLayerAtIndex instead of tileLayerAtPosition.

(WebCore::TileCache::setAcceleratesDrawing):
(WebCore::TileCache::setTileDebugBorderWidth):
(WebCore::TileCache::setTileDebugBorderColor):
Iterate over the hash map instead of the sublayers.

(WebCore::TileCache::resizeTileGrid):
Add the created layers to the map.

(WebCore::TileCache::tileLayerAtIndex):
Rename from tileLayerAtPoint to better reflect that this member function
returns a tile layer at the given index and not the given point.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@106397 268f45cc-cd09-0410-ab3c-d52691b4dbfc