Add some cases for the embed element

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>
Refine tests for the embed element

- Add _manual suffix to reftest filename
- Add a reference file embed_represent_nothing_ref.html
- Remove embed_pass_parameters.html and embed_type_unmatch.html
  as not good design
Update according to the new template

1. Update the code format
2. Update the reference specification

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>
Resolve issues according to review comments

1. Rename files
2. Change titles
3. Remove the tests duplicate with reflection

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>
Removed a test using an obsolete attribute

This test is using .olderShadowRoot which has been removed from the
spec. Therefore this test is obsolete.
These tests are using an obsolete attribute

These tests are using .olderShadowRoot which has been removed from the
spec. Therefore these are obsolete.
Nits

Corrected typos; ids match variable for readability (not needed per say
given Shadow DOM's scoping but...)
Adjusted queryselector to operate on the SR

I assume that querying from document into a Shadow Root isn't expected
to work. Made the query to operate on the SR which fixes the failing
test(s).
Rewritten to follow the latest spec

Adjusted expectations.
Obsolete

(This test is exercising /select/)
Removed incorrect test

As per the conclusion at https://bugs.webkit.org/show_bug.cgi?id=103479
this test was incorrect.
Obsolete tests

These tests excercice something that was removed from the spec.
Use "git submodule update --init --recursive".
Merge pull request #589 from KenjiBaheux/obsolete-tests-using-oldershadowroot

Removed tests using an obsolete attribute
Merge pull request #608 from w3c/sideshowbarker-readme

Make readme say to use "git submodule update --init --recursive" for initial submodule init, to ensure that the user gets what's needed in nested submodules (e.g., resources/webidl2)
Merge pull request #592 from KenjiBaheux/nits-navigation-tests

Nits
Merge pull request #593 from KenjiBaheux/fixed-queryselector-in-styles-test

Adjusted queryselector to operate on the SR
Merge pull request #594 from KenjiBaheux/updated-test-athost

Rewritten to follow the latest spec
Merge pull request #595 from KenjiBaheux/obsolete-select

Obsolete
Remove trailing whitespaces