Remove several packages from DEPS

Remove several packages from DEPS

Copied the corresponding code from pkg/web_components

R=whesse@google.com

Committed: https://github.com/dart-lang/sdk/commit/7a9cc03c090153c62562f326dd051b7be9dc519b

[kevmoo, 2017-07-18 04:58:55]

kevmoo@google.com changed reviewers:
+ sigmund@google.com, whesse@google.com

[kevmoo, 2017-07-18 04:58:56]

My understanding: the observatory has their own hard-wired set of dependencies

These should be fine to remove then – right?

[Bill Hesse, 2017-07-18 12:50:09]

LGTM.  How did you verify that the packages were not dependencies of other
packages in DEPS?

I do this by
checking an artificially constructed pubspec.yaml with all
the packages in DEPS, with their version minimums at the version specified in
DEPS.  Then I run pub get, to see that it finds a consistent solution, and look
at any packages that were updated or added.

[kevmoo, 2017-07-18 14:21:23]

Description was changed from

==========
Remove several packages from DEPS

Copied the corresponding code from pkg/web_components
==========

to

==========
Remove several packages from DEPS

Copied the corresponding code from pkg/web_components

R=whesse@google.com

Committed:
https://github.com/dart-lang/sdk/commit/7a9cc03c090153c62562f326dd051b7be9dc519b
==========

[kevmoo, 2017-07-18 14:21:24]

Committed patchset #1 (id:1) manually as
7a9cc03c090153c62562f326dd051b7be9dc519b (presubmit successful).

[Siggi Cherem (dart-lang), 2017-07-18 23:52:23]

https://codereview.chromium.org/2977333002/diff/1/DEPS
File DEPS (left):

https://codereview.chromium.org/2977333002/diff/1/DEPS#oldcode128
DEPS:128: "web_components_rev": "@6349e09f9118dce7ae1b309af5763745e25a9d61",
I don't believe we can remove webcomponents that easily.

Many tests are testing behavior that requires the polyfills to be loaded too.
Those tests likely have an HTML file that contains a script tag to load the .js
polyfills and the extra hooks for dart2js (search for 
`packages/web_components/webcomponents.js` and
`packages/web_components/dart_support.js`)