Auto merge of #14038 - upsuper:bug1294299, r=heycam

Add Element.style support for stylo

<!-- Please describe your changes on the following line: -->
This is the Servo side change of [bug 1294299](https://bugzilla.mozilla.org/show_bug.cgi?id=1294299) which has been reviewed by @heycam, @emilio, and @SimonSapin.

This should not be merged until the Gecko side change gets merged into mozilla-central.

r? @heycam

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14038)
<!-- Reviewable:end -->

components/style/binding_tools/regen.py

@@ -236,10 +236,12 @@ COMPILATION_TARGETS = {
         "target_dir": "../gecko_bindings",
         "blacklist_types": [
             "nsACString_internal",
+            "nsAString_internal",
         ],
         "raw_lines": [
-            "pub use nsstring::nsACString;",
+            "pub use nsstring::{nsACString, nsAString};",
             "type nsACString_internal = nsACString;",
+            "type nsAString_internal = nsAString;"
         ],
         "flags": [
             "--ignore-methods",

components/style/binding_tools/regen_atoms.py

@@ -32,14 +32,14 @@ def msvc32_symbolify(source, ident):
 
 
 class GkAtomSource:
-    PATTERN = re.compile('^GK_ATOM\((.+),\s*"(.*)"\)')
+    PATTERN = re.compile('^GK_ATOM\((?P<ident>.+),\s*"(?P<value>.*)"\)', re.M)
     FILE = "dist/include/nsGkAtomList.h"
     CLASS = "nsGkAtoms"
     TYPE = "nsIAtom"
 
 
 class CSSPseudoElementsAtomSource:
-    PATTERN = re.compile('^CSS_PSEUDO_ELEMENT\((.+),\s*"(.*)",')
+    PATTERN = re.compile('^CSS_PSEUDO_ELEMENT\((?P<ident>.+),\s*"(?P<value>.*)",', re.M)
     FILE = "dist/include/nsCSSPseudoElementList.h"
     CLASS = "nsCSSPseudoElements"
     # NB: nsICSSPseudoElement is effectively the same as a nsIAtom, but we need
@@ -48,16 +48,24 @@ class CSSPseudoElementsAtomSource:
 
 
 class CSSAnonBoxesAtomSource:
-    PATTERN = re.compile('^CSS_ANON_BOX\((.+),\s*"(.*)"\)')
+    PATTERN = re.compile('^CSS_ANON_BOX\((?P<ident>.+),\s*"(?P<value>.*)"\)', re.M)
     FILE = "dist/include/nsCSSAnonBoxList.h"
     CLASS = "nsCSSAnonBoxes"
     TYPE = "nsICSSAnonBoxPseudo"
 
 
+class CSSPropsAtomSource:
+    PATTERN = re.compile('^CSS_PROP_[A-Z]+\(\s*(?P<value>[^,]+),\s*(?P<ident>[^,]+)', re.M)
+    FILE = "dist/include/nsCSSPropList.h"
+    CLASS = "nsCSSProps"
+    TYPE = "nsICSSProperty"
+
+
 SOURCES = [
     GkAtomSource,
     CSSPseudoElementsAtomSource,
     CSSAnonBoxesAtomSource,
+    CSSPropsAtomSource,
 ]
 
 
@@ -95,10 +103,14 @@ def collect_atoms(objdir):
     atoms = []
     for source in SOURCES:
         with open(os.path.join(objdir, source.FILE)) as f:
-            for line in f.readlines():
-                result = re.match(source.PATTERN, line)
-                if result:
-                    atoms.append(Atom(source, result.group(1), result.group(2)))
+            content = f.read()
+        found = set()
+        for match in source.PATTERN.finditer(content):
+            ident = match.group('ident')
+            if ident in found:
+                continue
+            found.add(ident)
+            atoms.append(Atom(source, ident, match.group('value')))
     return atoms