Bug 1108917 - Part 1: Attempt to evict data from decoders in start-time order. r=ajones

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extra : rebase_source : c906ca08b4a984a7b3e2ef1cdcaea810b5f5777d
Bug 1108917 - Part 2: Allow eviction of entire decoders that are ahead of the current play position. r=ajones

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extra : rebase_source : fc7fbd06e9c0c65de1c5ecb07a7a355fe1f6fbe8
Bug 1109431 - Apply TimestampsFuzzyEqual rounding to the buffered ranges returned from multiple decoders. r=ajones

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extra : rebase_source : 1ca8f7910db619b90fdc9478bb0dc52a5d16693b