Move geometry classes from core/platform/graphics to platform/geometry

Move the basic geometry classes; FloatPoint3D, FloatPoint, FloatQuad,
FloatRect, FloatSize, IntPoint, IntRectExtent, IntRect, IntSize,
LayoutBoxExtent, LayoutPoint, LayoutRect, and LayoutSize from
core/platform/graphics and into the new platform module.

Also move the support enums TextDirection and WritingMode needed by
BoxExtent as well as AffineTransform and TransformationMatrix as they
are needed by FloatPoint (through the SVGPoint typedef).

BUG=297477
R=abarth@chromium.org, pdr@chromium.org

Review URL: https://codereview.chromium.org/25494003

git-svn-id: svn://svn.chromium.org/blink/trunk@158725 bbb929c8-8fbe-4397-9dbb-9b2b20218538