Don't pre-reserve massive amounts of memory in SVGGlyphMap.
Don't pre-reserve massive amounts of memory in SVGGlyphMap.

This reduces the size of SVGFontElement from 20KB_ to ~200 bytes.

R=pdr@chromium.org

Review URL: https://codereview.chromium.org/15941019

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@151616 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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