Issue #1620 - Use Intrinsic Aspect Ratio for Images

https://bugzilla.mozilla.org/show_bug.cgi?id=1547231
https://bugzilla.mozilla.org/show_bug.cgi?id=1559094
https://bugzilla.mozilla.org/show_bug.cgi?id=1633434
https://bugzilla.mozilla.org/show_bug.cgi?id=1565690
https://bugzilla.mozilla.org/show_bug.cgi?id=1602047

Make use of Aspect Ratios in Image frames before Images are loaded.
- Check for width and height HTML properties and create a ratio with them.
- Overwrite HTML size values with actual image dimensions on load.
- Collapse any frames with srcless images.

Comments:
dom/html/nsGenericHTMLElement.cpp:1483
layout/generic/nsImageFrame.cpp:289

layout/generic/crashtests/1633434.html

@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <script>
+      document.addEventListener('DOMContentLoaded', () => {
+        const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg')
+        svg.setAttribute('height', '6')
+        svg.setAttribute('width', '1pc')
+        document.documentElement.appendChild(svg)
+        svg.style.setProperty('height', '5%', undefined)
+        svg.width.baseVal.valueInSpecifiedUnits = 1.988164037240853e+38
+      })
+    </script>
+</head>
+</html>

layout/generic/crashtests/crashtests.list

@@ -644,3 +644,4 @@ load 1304441.html
 load 1316649.html
 load 1381134.html
 load 1381134-2.html
+load 1633434.html