Add <audio> and <video> player backends
These patches enables audio and video playing inside Servo.
It is bit hackish way to enable it, thus the purpose of this pull request is for an early request for comments.
It is tested with the current servo-media GStreamer backend in Linux.
~~The produced layout is not correct, since the elements after the video seems to be stacked behind, and the same with the scrolling bars.~~
~~There is no JavaScript interface yet~~, neither controls.
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ServoView: Add default constructor.
Android's `View` has multiple constructors. Currently only `ServoView(Context, AttributeSet)` is available. This constructor is usually used by Android when inflating a View from a layout XML file. However when creating the `View` in code no `AttributeSet` is available.
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Add framebuffer check for mark_as_dirty, #21691
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Check `bound_framebuffer` in each `mark_as_dirty` call, so that we don't dirty the canvas if we don't have a bound framebuffer.
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Add optional section to README for using lld-link on Windows
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Switching to lld-link as described in #21243 decreased Windows dev build times for 1-line changes from 20 minutes to 10 minutes for me. The last comment on that issue mentioned that a readme change might be welcome, hopefully this is useful 😄
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Since media processing is highly asynchronous, there is no need to
match one event with the other. Then error handling is done when
the player emits the EOS event.
The have_metadata attribute is not required anymore.
