Remove getMediaDevices interface.

LayoutTests/fast/mediastream/getMediaDevices-expected.txt

-Tests navigator.getMediaDevices
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-On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
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-PASS navigator.getMediaDevices(devicesCallback); did not throw exception.
-PASS After getMediaDevices
-PASS Devices returned.
-PASS devices.length is 3
-PASS devices[0].deviceId.length is > 0
-PASS devices[1].deviceId.length is > 0
-PASS devices[2].deviceId.length is > 0
-PASS devices[0].deviceId is not devices[1].deviceId
-PASS devices[0].deviceId is not devices[2].deviceId
-PASS devices[1].deviceId is not devices[2].deviceId
-PASS devices[0].kind is "audioinput"
-PASS devices[1].kind is "audiooutput"
-PASS devices[2].kind is "videoinput"
-PASS devices[0].label.length is > 0
-PASS devices[1].label.length is > 0
-PASS devices[2].label.length is > 0
-PASS devices[0].label is not devices[1].label
-PASS devices[0].label is not devices[2].label
-PASS devices[1].label is not devices[2].label
-PASS devices[0].groupId.length is > 0
-PASS devices[1].groupId.length is > 0
-PASS devices[2].groupId.length is > 0
-PASS devices[0].groupId is devices[1].groupId
-PASS devices[0].groupId is not devices[2].groupId
-PASS successfullyParsed is true
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-TEST COMPLETE
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