Fix 'will execute script' condition for creating custom elements in imports

Fix 'will execute script' condition for creating custom elements in imports

This CL fixes the 'will execute script' flag calculation
by fixing the definition lookup in
HTMLConstructionSite::lookUpCustomElementDefinition(),
and attributeChangedCallback() will be invoked
properly for custom elements parsed and created
synchronously in imports.

Upgrade case is not affected by this bug.

BUG=642839
Review-Url: https://codereview.chromium.org/2297853006
Cr-Commit-Position: refs/heads/master@{#416176}
(cherry picked from commit 94d61015c751d3d5c6ca9deedb0637cfcbbb1283)

Committed: https://chromium.googlesource.com/chromium/src/+/b3fdcae1aeaf6a1113f57cb7a35caf0cc6336c58

[kochi, 2016-09-05 03:35:45]

Description was changed from

==========
Fix 'will execute script' condition for creating custom elements in imports

This CL fixes the 'will execute script' flag calculation
by fixing the definition lookup in
HTMLConstructionSite::lookUpCustomElementDefinition(),
and attributeChangedCallback() will be invoked
properly for custom elements parsed and created
synchronously in imports.

Upgrade case is not affected by this bug.

BUG=642839

Review-Url: https://codereview.chromium.org/2297853006
Cr-Commit-Position: refs/heads/master@{#416176}
(cherry picked from commit 94d61015c751d3d5c6ca9deedb0637cfcbbb1283)
==========

to

==========
Fix 'will execute script' condition for creating custom elements in imports

This CL fixes the 'will execute script' flag calculation
by fixing the definition lookup in
HTMLConstructionSite::lookUpCustomElementDefinition(),
and attributeChangedCallback() will be invoked
properly for custom elements parsed and created
synchronously in imports.

Upgrade case is not affected by this bug.

BUG=642839

Review-Url: https://codereview.chromium.org/2297853006
Cr-Commit-Position: refs/heads/master@{#416176}
(cherry picked from commit 94d61015c751d3d5c6ca9deedb0637cfcbbb1283)

Committed:
https://chromium.googlesource.com/chromium/src/+/b3fdcae1aeaf6a1113f57cb7a35c...
==========

[kochi, 2016-09-05 03:35:50]

Committed patchset #1 (id:1) manually as
b3fdcae1aeaf6a1113f57cb7a35caf0cc6336c58.