Handle transformed descendants when drawing focus rings

Previously we use localToContainerPoint((0,0)) to calculate the offset
of a child when drawing focus rings. If the child is rotated, (0, 0)
won't be its top-left corner in container‘s coordinations.

Now use localToContainerQuad(childLocalFocusRingRect).enclosingBoundingBox().

Also updated RenderObject::absoluteFocusRingQuads() to be
transform-aware.

BUG=374168
TEST=transforms/transform-focus-ring.html

Review URL: https://codereview.chromium.org/288013005

git-svn-id: svn://svn.chromium.org/blink/trunk@175183 bbb929c8-8fbe-4397-9dbb-9b2b20218538