Mix rrect/ellipse/circle in GrOvalRenderer Batching.

    This patch creates two index buffers for GrOvalRenderer.  One Index Buffer for circle  (fill and stroke) + simple rrect (x and y radii are same) for fill and simple rrect (x and y radii are same for stroke.  The second index buffer for oval (ellipse) for fill and stroke, and for rrect where (x != y) for stroke and for fill.

    Both index buffers for circle and ellipse are pre-populated with 0, 1, 2, 2, 0, 3, 4, 5, 6, 6, 4, 7,.........
    Reasons of two index buffers are oval and circle has different shaders

    For circle and oval, 4 vertices are created 6 indices are being used.
    For rrect fill, 36 vertices are created and 54 indices are being used.
    For rrect stroke, 32 vertices are created 48 indices are being used.