Tests for AnimationNode methods
improving tests according review comments
improving tests according to review notes
Changes according review notes. AnimationNodeList has no forEach()
Sort the lists in Manifest.to_json.
Sort the elements of out_items directly in Manifest.to_json.

This commit does not change the generated file.
Merge pull request #1352 from Ms2ger/deterministic-manifest

Ensure the output of manifest.py is deterministic; r=darobin
Use backslash for url tests starting with #. Fixes #618
Merge pull request #1353 from zcorpan/urltestdata-comment

Use backslash for url tests starting with #. Fixes #618
Fix worker data: test pass condition. Fixes #475
Re-add a useful assertion in websockets. Fixes #522
worker postMessage(1, null) should throw, undefined should not. Fixes #491
Fix worker ErrorEvent test should use constructor and test non-support for legacy. Fixes #492
Use step_func in send-no-response-event-order.htm.
Remove VerifyResult from send-no-response-event-order.htm.

There's no point in this additional abstraction.
Don't use assert_array_equals
Check for TypeError
Merge pull request #1361 from Ms2ger/xhr-step

Cleanup send-no-response-event-order.htm; r=zcorpan
Merge pull request #1357 from zcorpan/fix-491

worker postMessage(1, null) should throw, undefined should not. Fixes #491; r=Ms2ger
Merge pull request #1358 from zcorpan/fix-492

Fix worker ErrorEvent test should use constructor and test non-support for legacy. Fixes #492; r=Ms2ger