Remove FileError interface

FileError was removed from File API [1] after Chrome had shipped the
functionality. Other browsers do not use it, returning a DOMError
instead. Using the `code` property has been logging deprecation
warnings since August 2013. The affected APIs will now yield
DOMExceptions instead (as DOMError is being removed from the platform
[2]). Script should inspect the `name` and `message` properties of the
error objects.

This affects:
* FileReader.error
* FileWriter.error
* FileSystem async API: passed to ErrorCallback on failure
* FileSystem sync API: thrown on failure




Cr-Commit-Position: refs/heads/master@{#406169}
50 files changed