[GridNG] Change IsLayoutGrid to IsLayoutGridIncludingNG

As above. This fixes a bunch of small issues. Some of the branches
are relatively difficult to reach due to layout ng being so prevalent,
but commented on the ones which clearly have associated tests.

Added a bunch of TODOs for behaviour which needs to be implemented.
Specifically:
 - devtools information.
 - computed-style grid-template-*, etc.
 - abspos invalidation.

Bug: 1045599
Change-Id: I0c4a7aae3381e49bf2e7e3bc80247c8c8dccc73f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2674359
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#850751}

css/css-grid/grid-item-percentage-quirk-001.html

@@ -0,0 +1,9 @@
+<!-- quirks mode -->
+<link rel="match" href="../../quirks/reference/green-100px-square-no-red.html">
+<link rel="help" href="https://quirks.spec.whatwg.org/#the-percentage-height-calculation-quirk">
+<p>There should be a filled green square below, and no red.</p>
+<div style="width: 100px; height: 100px; overflow: hidden; background: green;">
+  <div style="display: grid; position: relative; left: -20px;">
+    <canvas width=10 height=10 style="height: 200%; background: red;"></canvas>
+  </div>
+</div>

css/css-grid/grid-item-percentage-quirk-002.html

@@ -0,0 +1,9 @@
+<!-- quirks mode -->
+<link rel="match" href="../../quirks/reference/green-100px-square-no-red.html">
+<link rel="help" href="https://quirks.spec.whatwg.org/#the-percentage-height-calculation-quirk">
+<p>There should be a filled green square below, and no red.</p>
+<div style="width: 100px; height: 100px; overflow: hidden; background: green;">
+  <div style="display: grid; position: relative; left: -20px;">
+    <div width=10 height=10 style="height: 200%; width: 200px; background: red;"></div>
+  </div>
+</div>