Issue #1668 - Part 2: Visited color and auto support for caret-color property.

Mozilla's original implementation of this failed a couple of tests, but this seems to solve all the problems. Basically, the caret-color wasn't able to be set differently based on whether a link was visited, and the auto value implementation was incomplete. The only test we fail now is the one where you have grey text on a grey background and the caret is supposed to be visible, but I think that may have been removed from the spec. Even if it wasn't, no other browser supports it anyway.

dom/smil/nsSMILCSSProperty.cpp

@@ -194,6 +194,7 @@ nsSMILCSSProperty::IsPropertyAnimatable(nsCSSPropertyID aPropID)
   //   writing-mode
 
   switch (aPropID) {
+    case eCSSProperty_caret_color:
     case eCSSProperty_clip:
     case eCSSProperty_clip_rule:
     case eCSSProperty_clip_path:

layout/generic/nsFrame.cpp

@@ -1831,7 +1831,7 @@ nsIFrame::DisplayCaret(nsDisplayListBuilder* aBuilder,
 nscolor
 nsIFrame::GetCaretColorAt(int32_t aOffset)
 {
-  return StyleColor()->CalcComplexColor(StyleUserInterface()->mCaretColor);
+  return nsLayoutUtils::GetColor(this, eCSSProperty_caret_color);
 }
 
 bool

layout/style/nsRuleNode.cpp

@@ -5141,6 +5141,13 @@ nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
 {
   COMPUTE_START_INHERITED(UserInterface, ui, parentUI)
 
+  auto setComplexColor = [&](const nsCSSValue* aValue,
+                             StyleComplexColor nsStyleUserInterface::* aField) {
+    SetComplexColor<eUnsetInherit>(*aValue, parentUI->*aField,
+                                   StyleComplexColor::Auto(),
+                                   mPresContext, ui->*aField, conditions);
+  };
+
   // cursor: enum, url, inherit
   const nsCSSValue* cursorValue = aRuleData->ValueForCursor();
   nsCSSUnit cursorUnit = cursorValue->GetUnit();
@@ -5213,12 +5220,8 @@ nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
            NS_STYLE_POINTER_EVENTS_AUTO);
 
   // caret-color: auto, color, inherit
-  const nsCSSValue* caretColorValue = aRuleData->ValueForCaretColor();
-  SetComplexColor<eUnsetInherit>(*caretColorValue,
-                                 parentUI->mCaretColor,
-                                 StyleComplexColor::Auto(),
-                                 mPresContext,
-                                 ui->mCaretColor, conditions);
+  setComplexColor(aRuleData->ValueForCaretColor(),
+                  &nsStyleUserInterface::mCaretColor);
 
   COMPUTE_END_INHERITED(UserInterface, ui)
 }

layout/style/nsStyleContext.cpp

@@ -1255,6 +1255,17 @@ nsStyleContext::CalcStyleDifferenceInternal(StyleContextLike* aNewContext,
       }
     }
 
+    // NB: Calling Peek on |this|, not |thisVis| (see above).
+    if (!change && PeekStyleUserInterface()) {
+      const nsStyleUserInterface *thisVisUserInterface = thisVis->StyleUserInterface();
+      const nsStyleUserInterface *otherVisUserInterface = otherVis->StyleUserInterface();
+      if (thisVisUserInterface->mCaretColor !=
+          otherVisUserInterface->mCaretColor) {
+        change = true;
+      }
+    }
+
+
     if (change) {
       hint |= nsChangeHint_RepaintFrame;
     }
@@ -1487,6 +1498,9 @@ ExtractColor(nsCSSPropertyID aProperty,
     case StyleAnimationValue::eUnit_ComplexColor:
       return Some(aStyleContext->StyleColor()->
                   CalcComplexColor(val.GetStyleComplexColorValue()));
+    case StyleAnimationValue::eUnit_Auto:
+      return Some(aStyleContext->StyleColor()->
+                  CalcComplexColor(StyleComplexColor::Auto()));
     default:
       return Nothing();
   }
@@ -1508,7 +1522,8 @@ static const ColorIndexSet gVisitedIndices[2] = { { 0, 0 }, { 1, 0 } };
 nscolor
 nsStyleContext::GetVisitedDependentColor(nsCSSPropertyID aProperty)
 {
-  NS_ASSERTION(aProperty == eCSSProperty_color ||
+  NS_ASSERTION(aProperty == eCSSProperty_caret_color ||
+	       aProperty == eCSSProperty_color ||
                aProperty == eCSSProperty_background_color ||
                aProperty == eCSSProperty_border_top_color ||
                aProperty == eCSSProperty_border_right_color ||