Bug 1874065 - Make deprecated system color InfoBackground same as css-color-4 system color Canvas. r=morgan,emilio

Map `InfoBackground` to the `Canvas` to conform with [css-color-4 Appendix A: Deprecated CSS System Colors](https://www.w3.org/TR/css-color-4/#deprecated-system-colors) and update expected WPT and dom/canvas test results.

Differential Revision: https://phabricator.services.mozilla.com/D198215

dom/canvas/test/test_bug232227.html

@@ -25,7 +25,7 @@ function runTest(testCanvasColors) {
     [ "GrayText", 0x6D, 0x6D, 0x6D ],
     [ "Highlight", 0x33, 0x99, 0xFF ],
     [ "HighlightText", 0xFF, 0xFF, 0xFF ],
-    [ "InfoBackground", 0xFF, 0xFF, 0xE1 ],
+    [ "InfoBackground", 0xFF, 0xFF, 0xFF ], // deprecated, same as Canvas/Window (bug 1874065)
     [ "InfoText", 0x00, 0x00, 0x00 ], // deprecated, same as CanvasText/WindowText (bug 1803931)
     [ "Menu", 0xFF, 0xFF, 0xFF ], // deprecated, same as Canvas/Window (bug 1803930)
     [ "MenuText", 0x00, 0x00, 0x00 ], // deprecated, same as CanvasText/WindowText (bug 1873951)

testing/web-platform/meta/css/css-color/deprecated-sameas-011.html.ini

@@ -1,2 +0,0 @@
-[deprecated-sameas-011.html]
-  expected: FAIL

widget/nsXPLookAndFeel.cpp

@@ -657,7 +657,8 @@ nscolor nsXPLookAndFeel::GetStandinForNativeColor(ColorID aID,
       COLOR(Graytext, 0x6D, 0x6D, 0x6D)
       COLOR(Highlight, 0x33, 0x99, 0xFF)
       COLOR(Highlighttext, 0xFF, 0xFF, 0xFF)
-      COLOR(Infobackground, 0xFF, 0xFF, 0xE1)
+      // deprecated in CSS Color Level 4, same as Canvas/Window:
+      COLOR(Infobackground, 0xFF, 0xFF, 0xFF)
       // deprecated in CSS Color Level 4, same as Canvastext/Windowtext:
       COLOR(Infotext, 0x00, 0x00, 0x00)
       // deprecated in CSS Color Level 4, same as Canvas/Window:
@@ -1279,7 +1280,7 @@ static constexpr std::bitset<size_t(ColorID::End)> sNonNativeThemeStandinColors{
     BIT_FOR(Inactivecaptiontext) |
     // should match Canvas/Window:
     BIT_FOR(Appworkspace) | BIT_FOR(Background) | BIT_FOR(Inactivecaption) |
-    BIT_FOR(Menu) | BIT_FOR(Scrollbar) |
+    BIT_FOR(Infobackground) | BIT_FOR(Menu) | BIT_FOR(Scrollbar) |
     // should match CanvasText/WindowText:
     BIT_FOR(Activecaption) | BIT_FOR(Captiontext) | BIT_FOR(Infotext) |
     BIT_FOR(Menutext) |