Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-2_1/rev/dd10539a4bc7
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #23965 from davidflanagan/bug1064126-v2.1

Merge pull request #23921 from davidflanagan/bug1064126

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https://hg.mozilla.org/integration/gaia-2_1/rev/ad119a4eba51
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #23921 from davidflanagan/bug1064126

Bug 1064126: be more efficient with canvas memory r=russn(cherry picked from commit a5949ec98cf3ed7bb46d8c7b13678ff3c767c71c)
Bumping manifests a=b2g-bump