CSS: font-family initial value unspecified

https://drafts.csswg.org/css-fonts-4/#font-family-prop
Initial: depends on user agent

We can't simply have "times new roman"
in our test expectations, as Mac 10.10 .. 10.12 have
Times instead.

Bug: 966249
Change-Id: I091924585e05b2b085ab420ac553233f7346e79d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1695581
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Dominik Röttsches <drott@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676242}

third_party/blink/web_tests/TestExpectations

@@ -6255,6 +6255,3 @@ crbug.com/982289 virtual/gpu-rasterization/images/color-profile-image-canvas.htm
 crbug.com/982289 virtual/gpu-rasterization/images/color-profile-mask-image-svg.html [ Pass Failure ]
 crbug.com/982289 virtual/gpu-rasterization/images/ycbcr-with-cmyk-color-profile.html [ Pass Failure ]
 crbug.com/982289 virtual/gpu-rasterization/images/color-profile-image.html [ Pass Failure ]
-
-# Sheriff 2019-07-09
-crbug.com/966249 [ Mac ] external/wpt/css/css-fonts/inheritance.html [ Pass Failure ]

third_party/blink/web_tests/external/wpt/css/css-fonts/inheritance-expected.txt

 This is a testharness.js-based test.
-PASS Property font-family has initial value "times new roman"
 PASS Property font-family inherits
 PASS Property font-feature-settings has initial value normal
 PASS Property font-feature-settings inherits

third_party/blink/web_tests/external/wpt/css/css-fonts/inheritance.html

@@ -12,7 +12,6 @@
 <script src="/css/support/inheritance-testcommon.js"></script>
 <style>
   #box {
-    font: initial;
     font-size: medium;
   }
 </style>
@@ -25,10 +24,9 @@
 <script>
 'use strict';
 const box = document.getElementById('box');
-const initialFontFamily = getComputedStyle(box).fontFamily;
 const mediumFontSize = getComputedStyle(box).fontSize;
 
-assert_inherited('font-family', initialFontFamily, '"Not Initial!"');
+assert_inherited('font-family', null, '"Not Initial!"');  // Initial value depends on user agent.
 assert_inherited('font-feature-settings', 'normal', '"smcp", "swsh" 2');
 assert_inherited('font-kerning', 'auto', 'none');
 assert_inherited('font-size', mediumFontSize /* medium */, '123px');

third_party/blink/web_tests/external/wpt/css/support/inheritance-testcommon.js

@@ -33,6 +33,7 @@ function assert_initial(property, initial) {
  *                                  value.
  */
 function assert_inherited(property, initial, other) {
+  if (initial)
     assert_initial(property, initial);
 
   test(() => {