Auto merge of #104 - servo:empty-attr-selectors, r=emilio

Fix empty values and values with whitespace in attribute selectors

servo/servo#15394

Also use `?` syntax. I recommend looking at the two commits separately.

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Author: bors-servo

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "selectors"
-version = "0.15.2"
+version = "0.16.0"
 authors = ["Simon Sapin <simon.sapin@exyr.org>", "Alan Jeffrey <ajeffrey@mozilla.com>"]
 documentation = "https://docs.rs/selectors/"
 

src/matching.rs

@@ -419,6 +419,12 @@ fn matches_simple_selector<E>(
             relation_if!(element.match_attr_suffix(attr, value),
                          AFFECTED_BY_NON_COMMON_STYLE_AFFECTING_ATTRIBUTE_SELECTOR)
         }
+        SimpleSelector::AttrIncludesNeverMatch(..) |
+        SimpleSelector::AttrPrefixNeverMatch(..) |
+        SimpleSelector::AttrSubstringNeverMatch(..) |
+        SimpleSelector::AttrSuffixNeverMatch(..) => {
+            false
+        }
         SimpleSelector::NonTSPseudoClass(ref pc) => {
             relation_if!(element.match_non_ts_pseudo_class(pc.clone()),
                          AFFECTED_BY_STATE)