Add the GeometricPrecisionDisablesTypesettingFeatures flag

This patch adds the runtime enabled feature "GeometricPrecisionDisablesTypesettingFeatures"
which disables kerning and ligatures for text with text-rendering=
geometricPrecision. This matches the spec [1]. If there are no major
regressions we will remove this flag in roughly 6 weeks (~1 release).

[1] https://svgwg.org/svg2-draft/single-page.html#painting-TextRenderingProperty

BUG=338870

Review URL: https://codereview.chromium.org/141433027

git-svn-id: svn://svn.chromium.org/blink/trunk@166037 bbb929c8-8fbe-4397-9dbb-9b2b20218538