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/style/test/ListCSSProperties.cpp

@@ -106,6 +106,7 @@ const char *gInaccessibleProperties[] = {
     "-x-span",
     "-x-system-font",
     "-x-text-zoom",
+    "aspect-ratio",  // for now.
     "-moz-control-character-visibility",
     "-moz-script-level", // parsed by UA sheets only
     "-moz-script-size-multiplier",