auto merge of #831 : SimonSapin/servo/newnewcss, r=metajack

I started this in a [separate repository](https://github.com/SimonSapin/servo-style), and imported it with [git-subtree](https://github.com/git/git/blob/master/contrib/subtree/git-subtree.txt) into `servo/src/components/script/style` after some Rust minor upgrades.

I move this into the script crate because it’s gonna both need stuff there (the content tree, for selector matching) and be needed by stuff there (the HTML parser calls the CSS parser). As far as I know, we can not have circular dependencies between crates.

src/components/script/dom/bindings/codegen/CodegenRust.py

@@ -1247,10 +1247,10 @@ for (uint32_t i = 0; i < length; ++i) {
         dataLoc = "${declName}"
         #XXXjdm conversionBehavior should be used
         template = (
-            "match JSValConvertible::from_jsval::<%s>(${val}) {\n"
+            "match JSValConvertible::from_jsval(${val}) {\n"
             "  None => return 0,\n"
             "  Some(v) => %s = v\n"
-            "}" % (typeName, dataLoc))
+            "}" % (dataLoc,))
         declType = CGGeneric(typeName)
     if (defaultValue is not None and
         # We already handled IDLNullValue, so just deal with the other ones