style: Stop using PseudoElement::inherits_all.

This was done that way just because Servo didn't support the `all` property at
the time.

We should do it this way and optimize it if it's slow. Though I suspect that
most of stuff doesn't actually need to be inherited, my patch at bug 1498943
should make it much faster than what it would otherwise be.

components/style/servo/selector_parser.rs

@@ -221,41 +221,9 @@ impl PseudoElement {
         }
     }
 
-    /// For most (but not all) anon-boxes, we inherit all values from the
-    /// parent, this is the hook in the style system to allow this.
-    ///
-    /// FIXME(emilio): It's likely that this is broken in a variety of
-    /// situations, and what it really wants is just inherit some reset
-    /// properties...  Also, I guess it just could do all: inherit on the
-    /// stylesheet, though chances are that'd be kinda slow if we don't cache
-    /// them...
+    /// To be removed.
     pub fn inherits_all(&self) -> bool {
-        match *self {
-            PseudoElement::After |
-            PseudoElement::Before |
-            PseudoElement::Selection |
-            PseudoElement::DetailsContent |
-            PseudoElement::DetailsSummary |
-            // Anonymous table flows shouldn't inherit their parents properties in order
-            // to avoid doubling up styles such as transformations.
-            PseudoElement::ServoAnonymousTableCell |
-            PseudoElement::ServoAnonymousTableRow |
-            PseudoElement::ServoText |
-            PseudoElement::ServoInputText => false,
-
-            // For tables, we do want style to inherit, because TableWrapper is
-            // responsible for handling clipping and scrolling, while Table is
-            // responsible for creating stacking contexts.
-            //
-            // StackingContextCollectionFlags makes sure this is processed
-            // properly.
-            PseudoElement::ServoAnonymousTable |
-            PseudoElement::ServoAnonymousTableWrapper |
-            PseudoElement::ServoTableWrapper |
-            PseudoElement::ServoAnonymousBlock |
-            PseudoElement::ServoInlineBlockWrapper |
-            PseudoElement::ServoInlineAbsolute => true,
-        }
+        false
     }
 
     /// Covert non-canonical pseudo-element to canonical one, and keep a
@@ -585,7 +553,7 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
                 }
                 ServoInlineBlockWrapper
             },
-            "-servo-input-absolute" => {
+            "-servo-inline-absolute" => {
                 if !self.in_user_agent_stylesheet() {
                     return Err(location.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(name.clone())))
                 }

resources/servo.css

@@ -168,6 +168,33 @@ svg > * {
   display: none;
 }
 
+/*
+ * For most (but not all) anon-boxes, we inherit all values from the
+ * parent.
+ *
+ * Anonymous table flows shouldn't inherit their parents properties in order
+ * to avoid doubling up styles such as transformations. Same for text and such.
+ *
+ * For tables, we do want style to inherit, because TableWrapper is
+ * responsible for handling clipping and scrolling, while Table is
+ * responsible for creating stacking contexts.
+ *
+ * StackingContextCollectionFlags makes sure this is processed
+ * properly.
+ *
+ * FIXME(emilio): inheriting all is a very strong hammer, and it's likely
+ * broken for stuff like table backgrounds and such. Gecko explicitly inherits
+ * what it wants, which seems a bit better off-hand.
+ */
+*|*::-servo-anonymous-table,
+*|*::-servo-anonymous-table-wrapper,
+*|*::-servo-table-wrapper,
+*|*::-servo-anonymous-block,
+*|*::-servo-inline-block-wrapper,
+*|*::-servo-inline-absolute {
+    all: inherit;
+}
+
 /* style for text node. */
 *|*::-servo-text {
     margin: 0;
@@ -239,10 +266,16 @@ svg > * {
     margin: 0;
 }
 
-/* The outer fragment wrapper of an inline absolute hypothetical fragment. */
+/* The outer fragment wrapper of an inline absolute hypothetical fragment.
+ *
+ * FIXME(emilio): This was disabled because of a typo in the CSS parser,
+ * re-enable or figure out why it's not needed.
+
 *|*::-servo-inline-absolute {
     clip: auto;
     border: none;
     padding: 0;
     margin: 0;
 }
+
+*/