Bug 1074591 (part 1) - Allow JSON collections to be printed on a single line. r=froydnj.

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extra : rebase_source : d576a70d2d1ff83311ab8cce849ec0b5a6b3fa80
Bug 1074591 (part 2) - Remove Pointer{Element,Property}() from JSONWriter. r=froydnj.

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extra : rebase_source : db07aa93df880e201eba866cb791ccaa245f0ef8
Bug 1074591 (part 3) - Fix unbounded growth in JSONWriter's vectors(!). r=froydnj.

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extra : rebase_source : 364c0295c0b86e0f29dac3772acadbd0e1ab9d9f