style: Support css use counters for unimplemented properties.

For developing properties, we will handle them in an other bug.

Besides, I use an iframe for the test because we create a use counter in
the constructor of Document, which use the prefs to decide what kind of
properties we want to record. So, in the test, we have to reload iframe
to make sure we re-create the document, so does the use counter, to make
sure the prefs work properly.

The two prefs affect the css use counters:
1. layout.css.use-counters.enabled: Allocate use counters, and record
   non-custom properties.
2. layout.css.use-counters-unimplemented.enabled: Record all unimplmented
   properties into the use counters.

If we disable layout.css.use-counters.enblaed, we don't create use counters
object, so layout.css.use-counters-unimplemented.enabled doesn't work,
either.

Differential Revision: https://phabricator.services.mozilla.com/D43860

components/style/properties/counted_unknown_properties.py

@@ -0,0 +1,128 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following properties are under development, so they are not in this list.
+# FIXME: We should handle the developing properties properly by Bug 1577358:
+#    "backdrop-filter",
+#    "text-decoration-skip-ink",
+#    "column-span",
+#    "offset-distance",
+#    "offset-path",
+#    "offset-rotate"
+COUNTED_UNKNOWN_PROPERTIES = [
+    "-webkit-font-smoothing",
+    "zoom",
+    "-webkit-tap-highlight-color",
+    "speak",
+    "text-size-adjust",
+    "-webkit-font-feature-settings",
+    "-webkit-user-drag",
+    "size",
+    "-webkit-clip-path",
+    "orphans",
+    "widows",
+    "-webkit-user-modify",
+    "-webkit-margin-before",
+    "-webkit-margin-after",
+    "tab-size",
+    "-webkit-margin-start",
+    "-webkit-column-break-inside",
+    "-webkit-padding-start",
+    "-webkit-margin-end",
+    "-webkit-box-reflect",
+    "-webkit-print-color-adjust",
+    "-webkit-mask-box-image",
+    "-webkit-line-break",
+    "-webkit-text-security",
+    "alignment-baseline",
+    "-webkit-writing-mode",
+    "baseline-shift",
+    "-webkit-hyphenate-character",
+    "page",
+    "text-underline-position",
+    "-webkit-highlight",
+    "background-repeat-x",
+    "-webkit-padding-end",
+    "background-repeat-y",
+    "-webkit-text-emphasis-color",
+    "-webkit-margin-top-collapse",
+    "-webkit-rtl-ordering",
+    "-webkit-padding-before",
+    "-webkit-text-decorations-in-effect",
+    "-webkit-border-vertical-spacing",
+    "-webkit-locale",
+    "-webkit-padding-after",
+    "-webkit-border-horizontal-spacing",
+    "color-rendering",
+    "-webkit-column-break-before",
+    "-webkit-transform-origin-x",
+    "-webkit-transform-origin-y",
+    "-webkit-text-emphasis-position",
+    "buffered-rendering",
+    "-webkit-text-orientation",
+    "-webkit-text-combine",
+    "-webkit-text-emphasis-style",
+    "-webkit-text-emphasis",
+    "d",
+    "-webkit-mask-box-image-width",
+    "-webkit-mask-box-image-source",
+    "-webkit-mask-box-image-outset",
+    "-webkit-mask-box-image-slice",
+    "-webkit-mask-box-image-repeat",
+    "-webkit-margin-after-collapse",
+    "-webkit-border-before-color",
+    "-webkit-border-before-width",
+    "-webkit-perspective-origin-x",
+    "-webkit-perspective-origin-y",
+    "-webkit-margin-before-collapse",
+    "-webkit-border-before-style",
+    "scroll-snap-stop",
+    "-webkit-margin-bottom-collapse",
+    "-webkit-ruby-position",
+    "-webkit-column-break-after",
+    "-webkit-margin-collapse",
+    "offset",
+    "-webkit-border-before",
+    "-webkit-border-end",
+    "-webkit-border-after",
+    "-webkit-border-start",
+    "-webkit-min-logical-width",
+    "-webkit-logical-height",
+    "-webkit-transform-origin-z",
+    "-webkit-font-size-delta",
+    "-webkit-logical-width",
+    "-webkit-max-logical-width",
+    "-webkit-min-logical-height",
+    "-webkit-max-logical-height",
+    "-webkit-border-end-color",
+    "-webkit-border-end-width",
+    "-webkit-border-start-color",
+    "-webkit-border-start-width",
+    "-webkit-border-after-color",
+    "-webkit-border-after-width",
+    "-webkit-border-end-style",
+    "-webkit-border-after-style",
+    "-webkit-border-start-style",
+    "-webkit-mask-repeat-x",
+    "-webkit-mask-repeat-y",
+    "user-zoom",
+    "min-zoom",
+    "-webkit-box-decoration-break",
+    "orientation",
+    "max-zoom",
+    "-webkit-app-region",
+    "-webkit-column-rule",
+    "-webkit-column-span",
+    "-webkit-column-gap",
+    "-webkit-shape-outside",
+    "-webkit-column-rule-width",
+    "-webkit-column-count",
+    "-webkit-opacity",
+    "-webkit-column-width",
+    "-webkit-shape-image-threshold",
+    "-webkit-column-rule-style",
+    "-webkit-columns",
+    "-webkit-column-rule-color",
+    "-webkit-shape-margin",
+]