Support SVGUseElement in Polymer.dart element

[DartBot]

This issue was originally filed by @ggirou

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What steps will reproduce the problem?
svg:use tag doesn't work inside a Polymer element:

<polymer-element name="x-test">
  <template>
  <svg viewBox = "0 0 1000 1000" version = "1.1">
      <defs>
          <!-- A circle of radius 200 -->
          <circle id = "s1" cx = "200" cy = "200" r = "200" fill = "yellow" stroke = "black" stroke-width = "3"/>
          <!-- An ellipse (rx=200,ry=150) -->
          <ellipse id = "s2" cx = "200" cy = "150" rx = "200" ry = "150" fill = "salmon" stroke = "black" stroke-width = "3"/>
      </defs>
      <use x = "100" y = "100" xlink:href = "#s1"/>
      <use x = "100" y = "650" xlink:href = "#s2"/>
  </svg>
  </template>
  <script type="application/dart" src="test.dart"></script>
</polymer-element>

What is the expected output? What do you see instead?
We should see a circle and an ellipse.

What version of the product are you using? On what operating system?
Dart Editor version 1.2.0.release (STABLE)
Dart SDK version 1.2.0
polymer 0.9.5

Please provide any additional information below.
Similar bugs in Polymer.js:
https://github.com/Polymer/ShadowDOM/issues/342
Polymer/polymer#388

[iposva-google]

Added Area-Polymer, Triaged labels.

[jmesserly]

Removed Area-Polymer label.
Added Pkg-Polymer, Area-Pkg labels.

[sigmundch]

Does it still fail now with the latest polymer (0.11.0)?

Seems like the bug in ShadowDOM has been fixed for a while, and it's quite possible that we got fixed when we updated web_components recently (which brings in all the changes from ShadowDOM up to date in our pacakges).

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Added this to the Later milestone.
Removed Priority-Unassigned label.
Added Priority-Medium, NeedsInfo labels.

[DartBot]

This comment was originally written by @ggirou

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It works now.
Thanks!

[sigmundch]

Added Polymer-P-2 label.

[sigmundch]

Removed this from the Later milestone.

[sigmundch]

Removed Polymer-P-2 label.
Added Polymer-Milestone-Later label.

[sigmundch]

Removed Polymer-Milestone-Later label.
Added PolymerMilestone-Later label.

[sigmundch]

Awesome

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Added AssumedStale label.

[DartBot]

This issue has been moved to dart-archive/polymer-dart#125.