Bug 849207 - Use __declspec(dllexport) for exporting skia C++ symbols. r=gwright

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extra : rebase_source : 333c7fcc334db6f6969995f0ff5fac8bb9607e74
Bug 849198 - Merge nsPluginSafety.h into nsNPAPIPluginInstance.h r=roc

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extra : rebase_source : b5e71211edce0b30f92033010d47b9a303f2c3bf