Weblinks API for embedded scenario using Gerrit.Nav interface

Gerrit.Nav.setup() now takes a weblinks generator function as a third
parameter. Here's the function signature:

``` js
Gerrit.Nav.setup(navigate, generateUrl, generateWeblinks)
```

Weblinks generator function takes single payload parameter with
`type` property that determines which part of the UI is the consumer of
the weblinks. `type` property can be one of `file`, `change`, or
`patchset`.

For `file` type, payload will also contain string properties:
`repo`, `commit`, `file`.

For `pachset` type, payload will also contain string properties:
`repo`, `commit`.

For `change` type, payload will also contain string properties:
`repo`, `commit`.

If server provides weblinks, those will be passed as `options.weblinks`
property on the main payload object.

Change-Id: I0d9de3a295435304e2b6aad551112440075cf098

polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html

diff --git a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
index 21598a2..532b928 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
@@ -15,8 +15,8 @@
 -->
 
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
-
 <link rel="import" href="../../../behaviors/gr-patch-set-behavior/gr-patch-set-behavior.html">
+<link rel="import" href="../../../styles/shared-styles.html">
 <link rel="import" href="../../shared/gr-button/gr-button.html">
 <link rel="import" href="../../shared/gr-rest-api-interface/gr-rest-api-interface.html">
 <link rel="import" href="../gr-diff-builder/gr-diff-builder.html">
@@ -24,7 +24,6 @@
 <link rel="import" href="../gr-diff-highlight/gr-diff-highlight.html">
 <link rel="import" href="../gr-diff-selection/gr-diff-selection.html">
 <link rel="import" href="../gr-syntax-themes/gr-theme-default.html">
-<link rel="import" href="../../../styles/shared-styles.html">
 
 <script src="../../../scripts/hiddenscroll.js"></script>