[As discussed](https://github.com/mozilla/servo/wiki/Meeting-2013-07-01#css), even though this parser is not used yet, having it built and tested with the rest of Servo helps ensure it does not bitrot.

[As discussed](https://github.com/mozilla/servo/wiki/Meeting-2013-07-01#css), even though this parser is not used yet, having it built and tested with the rest of Servo helps ensure it does not bitrot.

Fix typo in event_loadstart.html.

Use strongly typed geometry - Part 1

Part one of a series of pull requests to convert untyped geometry into strongly typed geometry.
This PR adds LayerPixel, ParentLayerPixel and WorldPixel, as well as the corresponging Rect, Point and Size structures, and converts good chunk of the Rect<f32> that I could identify as LayerRect.

In order to avoid churn in the public API, I postponed converting most of the webrender_trait types, but this will be done as soon as the webrender internals are properly typed. As a result of the step-by-step approach, this PR adds some unpleasant ```LayerFoo::from_untyped``` and ```foo.to_untyped``` at places, but the end goal is to have almost none of them in the end. I hope to land things progressively, though, because this type of changeset is time-consuming to rebase.

The added units are inspired from gecko's units (Layer/ParentLayer) and some of the webrneder terminology (World). Don't hesitate to propose other names.

This needs a careful review, in particular for LayerPixel vs ParentLayerPixel.

r? @glennw @kvark @staktrace

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…jang

Bump cbindgen from 0.14.2 to 0.14.6

Bumps [cbindgen](https://github.com/eqrion/cbindgen) from 0.14.2 to 0.14.6.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/eqrion/cbindgen/blob/master/CHANGES">cbindgen's changelog</a>.</em></p>
<blockquote>
<h2>0.14.6</h2>
<pre><code> * Fixed the builds with older versions of rustc.
</code></pre>
<h2>0.14.5</h2>
<pre><code> * Add support to specify line ending style ([#568](mozilla/cbindgen#568))
 * Add cbindgen:ptrs-as-arrays annotation to allow making function
   arguments C/C++ arrays.
</code></pre>
<h2>0.14.4</h2>
<pre><code> * Allow to override the mangling separator ([#502](mozilla/cbindgen#502))
<ul>
<li>
<p>cbindgen now handles better having ZSTs in template parameters, and
default template parameters (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/563">#563</a>).</p>
</li>
<li>
<p>Support for annotating nonnull pointers (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/558">#558</a>)</p>
</li>
<li>
<p>Fixed bitflags that overflow a signed integer (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/556">#556</a>)</p>
</li>
<li>
<p>Support for wildcard argument names (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/550">#550</a>)</p>
</li>
<li>
<p>Support for the never return type, with configurable annotation (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/549">#549</a>)</p>
</li>
<li>
<p>Properly reject arrays as function arguments (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/540">#540</a>)
</code></pre></p>
</li>
</ul>
<h2>0.14.3</h2>
<pre><code> * Introduce cbindgen:ignore comment annotation, to allow ignoring items or modules. ([#519](mozilla/cbindgen#519))
 * Support for casts in constant expressions. ([#526](mozilla/cbindgen#526))
 * Make a non-fatal error a warning message. ([#535](mozilla/cbindgen#535))
 * Add a --metadata option to the CLI, to allow passing pre-computed cargo metadata. ([#538](mozilla/cbindgen#538))
</code></pre>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/eqrion/cbindgen/commit/e4da7d39a6d1481420440b37dcfe85d7ea4527d5"><code>e4da7d3</code></a> v0.14.6</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/1e46e53ae22b1d85bc794911dd750543e374bad7"><code>1e46e53</code></a> v0.14.5</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/fe656442a562ad1c7c19706d7b068492ecf58230"><code>fe65644</code></a> Document ptrs-as-arrays annotation</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/07c3aed03e6a3b53a580f8c6cfc4c9ea446104bb"><code>07c3aed</code></a> Add ptrs-as-arrays tests</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/ee4638ab10f4a7dcf9a8abd3b5fc2e2463dfcde5"><code>ee4638a</code></a> Add an annotation to represent pointers as arrays</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/73ea04c2b0f8926ebb1491ab311e591721d5dbd2"><code>73ea04c</code></a> Add badge to README</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/6b56082be8403c9dfe237cf0d4274369b7a83cd9"><code>6b56082</code></a> Replace travis with Github Actions</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/fec6bdad8cd9a0d37d506a6033ae3ee21c4f6989"><code>fec6bda</code></a> Fix clippy warnings</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/3ca0e75ed906ae505740657647b08e04cd844f14"><code>3ca0e75</code></a> Add support for specifying line ending style (<a href="https://github-redirect.dependabot.com/eqrion/cbindgen/issues/568">#568</a>)</li>
<li><a href="https://github.com/eqrion/cbindgen/commit/83cdbd897f02eaecb090a3f216899dcc14b43959"><code>83cdbd8</code></a> Release v.0.14.4</li>
<li>Additional commits viewable in <a href="https://github.com/eqrion/cbindgen/compare/v0.14.2...v0.14.6">compare view</a></li>
</ul>
</details>
<br />

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