Remove 'speak-as' from CSS.supports() API WPT

CSS.supports(property, value) is for CSS properties, not descriptors.
Since 'speak-as' only acts as a descriptor, this CL removes it from the
test.

This is also for exposing 'speak-as' to web tests: crrev.com/c/2530523

Bug: 687225
Change-Id: I1ee9cc6017ae4e4b2bba5a7c5c5f93c361600982
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2531493
Auto-Submit: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826220}

third_party/blink/web_tests/external/wpt/css/css-conditional/js/CSS-supports-CSSStyleDeclaration-expected.txt

 This is a testharness.js-based test.
-Found 1522 tests; 1497 PASS, 25 FAIL, 0 TIMEOUT, 0 NOTRUN.
+Found 1520 tests; 1495 PASS, 25 FAIL, 0 TIMEOUT, 0 NOTRUN.
 PASS -apple-color-filter: _camel_cased_attribute v. CSS.supports
 PASS -apple-color-filter: _webkit_cased_attribute must only exist for -webkit-
 PASS -apple-color-filter: _dashed_attribute v. CSS.supports
@@ -1347,8 +1347,6 @@ PASS shape-rendering: _camel_cased_attribute v. CSS.supports
 PASS shape-rendering: _dashed_attribute v. CSS.supports
 PASS size: _camel_cased_attribute v. CSS.supports
 PASS speak: _camel_cased_attribute v. CSS.supports
-PASS speak-as: _camel_cased_attribute v. CSS.supports
-PASS speak-as: _dashed_attribute v. CSS.supports
 FAIL src: _camel_cased_attribute v. CSS.supports assert_equals: expected true but got false
 PASS stop-color: _camel_cased_attribute v. CSS.supports
 PASS stop-color: _dashed_attribute v. CSS.supports

third_party/blink/web_tests/external/wpt/css/css-conditional/js/CSS-supports-CSSStyleDeclaration.html

@@ -612,7 +612,6 @@ const properties = [
   "shape-rendering",
   "size",
   "speak",
-  "speak-as",
   "src",
   "stop-color",
   "stop-opacity",