Bug 1102584 - patch 3 - Enable support for the actualBoundingBox* attributes of TextMetrics. r=lsalzman

This is unaffected by the differences in font metrics between platform back-ends,
so should be safe to ship without significant risk that it'll be unstable or need
to be revised in future.

Depends on D59679

Differential Revision: https://phabricator.services.mozilla.com/D59680

--HG--
extra : moz-landing-system : lando

modules/libpref/init/StaticPrefList.yaml

@@ -2394,7 +2394,7 @@
 
 - name: dom.textMetrics.actualBoundingBox.enabled
   type: bool
-  value: false
+  value: true
   mirror: always
 
 - name: dom.textMetrics.baselines.enabled

testing/web-platform/meta/2dcontext/drawing-text-to-the-canvas/2d.text.measure.actualBoundingBox.html.ini

@@ -1,4 +0,0 @@
-[2d.text.measure.actualBoundingBox.html]
-  [Testing actualBoundingBox]
-    expected: FAIL
-

testing/web-platform/meta/html/dom/idlharness.https.html.ini

@@ -189,9 +189,6 @@ prefs: [dom.security.featurePolicy.enabled:true, dom.security.featurePolicy.expe
   [Navigator interface: calling unregisterProtocolHandler(DOMString, USVString) on window.navigator with too few arguments must throw TypeError]
     expected: FAIL
 
-  [TextMetrics interface: attribute actualBoundingBoxAscent]
-    expected: FAIL
-
   [OffscreenCanvas interface: existence and properties of interface prototype object]
     expected: FAIL
 
@@ -330,18 +327,12 @@ prefs: [dom.security.featurePolicy.enabled:true, dom.security.featurePolicy.expe
   [Stringification of window.applicationCache]
     expected: FAIL
 
-  [TextMetrics interface: attribute actualBoundingBoxDescent]
-    expected: FAIL
-
   [OffscreenCanvasRenderingContext2D interface: operation isPointInPath(unrestricted double, unrestricted double, CanvasFillRule)]
     expected: FAIL
 
   [VideoTrack interface: attribute language]
     expected: FAIL
 
-  [TextMetrics interface: attribute actualBoundingBoxLeft]
-    expected: FAIL
-
   [VideoTrackList interface: attribute onremovetrack]
     expected: FAIL
 
@@ -510,9 +501,6 @@ prefs: [dom.security.featurePolicy.enabled:true, dom.security.featurePolicy.expe
   [External interface: operation IsSearchProviderInstalled()]
     expected: FAIL
 
-  [TextMetrics interface: attribute actualBoundingBoxRight]
-    expected: FAIL
-
   [SVGElement interface: attribute nonce]
     expected: FAIL