Bug 1407888 part 2 - Make ServoStyleRuleMap::FillTableFromStyleSheet not make unique inner. r=heycam

MozReview-Commit-ID: 1I7sawfjcnl

--HG--
extra : rebase_source : 620cc19b3826d557e5a255b1bee2417b073da799

layout/inspector/ServoStyleRuleMap.cpp

@@ -11,6 +11,7 @@
 #include "mozilla/ServoStyleRule.h"
 #include "mozilla/ServoStyleSet.h"
 #include "mozilla/ServoImportRule.h"
+#include "mozilla/StyleSheetInlines.h"
 
 #include "nsDocument.h"
 #include "nsStyleSheetService.h"
@@ -175,7 +176,19 @@ void
 ServoStyleRuleMap::FillTableFromStyleSheet(ServoStyleSheet* aSheet)
 {
   if (aSheet->IsComplete()) {
-    FillTableFromRuleList(aSheet->GetCssRulesInternal());
+    // Users of ServoStyleRuleMap should ensure any non-XBL complete
+    // stylesheet has already had a unique inner, and XBL stylesheets
+    // are not expected to ever change, so it's fine to construct the
+    // rule list without a unique inner.
+    // This is important because inner of XBL stylesheets is not made
+    // unique by EnsureSafeToHandOutCSSRules, and even if it is, the new
+    // unique inner may not be taken to restyle properly, so we may end
+    // up not being able to match rules there anyway.
+    MOZ_ASSERT(aSheet->HasUniqueInner() || mStyleSet->IsForXBL(),
+               "Non-XBL stylesheets should be made unique before "
+               "initializing ServoStyleRuleMap");
+    FillTableFromRuleList(
+      aSheet->GetCssRulesInternal(/* aRequireUniqueInner = */ false));
   }
 }
 

layout/style/ServoStyleSet.h

@@ -478,6 +478,9 @@ public:
                        ServoStyleContext* aNewLayoutParent,
                        Element* aElement);
 
+  bool IsMaster() const { return mKind == Kind::Master; }
+  bool IsForXBL() const { return mKind == Kind::ForXBL; }
+
 private:
   friend class AutoSetInServoTraversal;
   friend class AutoPrepareTraversal;
@@ -489,9 +492,6 @@ private:
    */
   const SnapshotTable& Snapshots();
 
-  bool IsMaster() const { return mKind == Kind::Master; }
-  bool IsForXBL() const { return mKind == Kind::ForXBL; }
-
   /**
    * Resolve all ServoDeclarationBlocks attached to mapped
    * presentation attributes cached on the document.

layout/style/ServoStyleSheet.cpp

@@ -393,10 +393,15 @@ ServoStyleSheet::Clone(StyleSheet* aCloneParent,
 }
 
 ServoCSSRuleList*
-ServoStyleSheet::GetCssRulesInternal()
+ServoStyleSheet::GetCssRulesInternal(bool aRequireUniqueInner)
 {
   if (!mRuleList) {
-    EnsureUniqueInner();
+    MOZ_ASSERT(HasUniqueInner() || aRequireUniqueInner || !mDocument,
+               "Not requiring unique inner for stylesheet associated "
+               "with document may have undesired behavior");
+    if (aRequireUniqueInner) {
+      EnsureUniqueInner();
+    }
 
     RefPtr<ServoCssRules> rawRules =
       Servo_StyleSheet_GetRules(Inner()->mContents).Consume();

layout/style/ServoStyleSheet.h

@@ -120,7 +120,7 @@ public:
 
   // Internal GetCssRules method which do not have security check and
   // completelness check.
-  ServoCSSRuleList* GetCssRulesInternal();
+  ServoCSSRuleList* GetCssRulesInternal(bool aRequireUniqueInner = true);
 
   // Returns the stylesheet's Servo origin as an OriginFlags value.
   OriginFlags GetOrigin();

layout/style/StyleSheet.cpp

@@ -450,7 +450,7 @@ StyleSheet::EnsureUniqueInner()
              "unexpected number of outers");
   mDirty = true;
 
-  if (mInner->mSheets.Length() == 1) {
+  if (HasUniqueInner()) {
     // already unique
     return;
   }

layout/style/StyleSheet.h

@@ -138,6 +138,7 @@ public:
 
   bool IsModified() const { return mDirty; }
 
+  inline bool HasUniqueInner() const;
   void EnsureUniqueInner();
 
   // Append all of this sheet's child sheets to aArray.

layout/style/StyleSheetInlines.h

@@ -129,6 +129,12 @@ StyleSheet::GetIntegrity(dom::SRIMetadata& aResult) const
   aResult = SheetInfo().mIntegrity;
 }
 
+bool
+StyleSheet::HasUniqueInner() const
+{
+  return mInner->mSheets.Length() == 1;
+}
+
 }
 
 #endif // mozilla_StyleSheetInlines_h