Bug 1101742 - Fix OmxDecoder::mIsVideoSeeking r= cajbir a=bajaj

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extra : rebase_source : 6258573d8375421f74109d4dbad157b9dad77f25
Backed out changeset 1b1134490959 (bug 998916) for frequent WebGL crashes/asserts.

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extra : rebase_source : e7b7f6b25a4f93d5b1491444eac1c1fa273e1e7d