script: add skeleton implementation of FontFace API (#35262)

This patch implements the `FontFace` interface, but with some caveats

1. The interface is only exposed on `Window`. Support for Workers will
   be handled in the future.
2. The concept of `css-connected` `FontFace` is not implemented, so
   `@font-face` rules in stylesheets will not be represented in the DOM.
3. The constructor only supports using `url()` strings as source
   and `ArrayBuffer` and `ArrayBufferView` are not supported yet.

A skeleton implementation of the `load` method of `FontFaceSet` is also
implemented in this patch. The intention is to support some web pages
that don't load without this method.

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>

tests/wpt/meta/html/canvas/offscreen/text/2d.text.draw.fill.maxWidth.fontface.html.ini

@@ -1,4 +0,0 @@
-[2d.text.draw.fill.maxWidth.fontface.html]
-  [fillText works on @font-face fonts]
-    expected: FAIL
-

tests/wpt/meta/html/canvas/offscreen/text/2d.text.measure.width.empty.html.ini

@@ -1,6 +1,3 @@
 [2d.text.measure.width.empty.html]
   [The empty string has zero width for OffscreenCanvas]
     expected: FAIL
-
-  [The empty string has zero width]
-    expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.condensed.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.condensed.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.expanded.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.expanded.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.extra-condensed.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.extra-condensed.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.extra-expanded.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.extra-expanded.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.normal.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.normal.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.semi-condensed.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.semi-condensed.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.semi-expanded.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.semi-expanded.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.ultra-condensed.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.ultra-condensed.html]
+  expected: FAIL

tests/wpt/meta/html/canvas/offscreen/text/canvas.2d.fontStretch.ultra-expanded.html.ini

@@ -0,0 +1,2 @@
+[canvas.2d.fontStretch.ultra-expanded.html]
+  expected: FAIL