Extend the test runner so that we can choose to run only a specific test file.
Refactor SourceMapConsumer and SourceMapGenerator to share the same internal
representation of a single mapping, and to share comparators of those mappings.
Add SourceMapConsumer.fromSourceMap to create SourceMapConsumer instances from
SourceMapGenerator instances.
Use for loops instead of .forEach for some perf gains
Merge pull request #78 from fitzgen/source-map-consumer-from-source-map

Add `SourceMapConsumer.fromSourceMap`
Add build script, _generateSourcesContent should handle null sourcesContents, better invalid mapping message.
Assign 'sourceMap' to 'this' instead of 'window' so that browser builds work inside workers.
Merge pull request #80 from fitzgen/work-with-workers

Support for workers
Merge pull request #79 from fitzgen/source-map-consumer-from-source-map

Changes from patch for bug 917963