Add mechanism for returning computed value name of certain longhand properties of our fake shorthands. (Bug 531585) r=bzbarsky

layout/style/nsCSSPropList.h

@@ -717,7 +717,8 @@ CSS_PROP_BORDER(
     border_left_color_value,
     X,
     CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED,
+        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mBorderColor.mLeft,
     eCSSType_Value,
@@ -773,7 +774,8 @@ CSS_PROP_BORDER(
     border-left-style-value,
     border_left_style_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mBorderStyle.mLeft,
     eCSSType_Value,
@@ -815,7 +817,8 @@ CSS_PROP_BORDER(
     border-left-width-value,
     border_left_width_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mBorderWidth.mLeft,
     eCSSType_Value,
@@ -863,7 +866,8 @@ CSS_PROP_BORDER(
     border_right_color_value,
     X,
     CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED,
+        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mBorderColor.mRight,
     eCSSType_Value,
@@ -919,7 +923,8 @@ CSS_PROP_BORDER(
     border-right-style-value,
     border_right_style_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mBorderStyle.mRight,
     eCSSType_Value,
@@ -961,7 +966,8 @@ CSS_PROP_BORDER(
     border-right-width-value,
     border_right_width_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mBorderWidth.mRight,
     eCSSType_Value,
@@ -1651,7 +1657,8 @@ CSS_PROP_MARGIN(
     margin-left-value,
     margin_left_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mMargin.mLeft,
     eCSSType_Value,
@@ -1693,7 +1700,8 @@ CSS_PROP_MARGIN(
     margin-right-value,
     margin_right_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mMargin.mRight,
     eCSSType_Value,
@@ -1958,7 +1966,8 @@ CSS_PROP_PADDING(
     padding-left-value,
     padding_left_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mPadding.mLeft,
     eCSSType_Value,
@@ -2000,7 +2009,8 @@ CSS_PROP_PADDING(
     padding-right-value,
     padding_right_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
+        CSS_PROPERTY_REPORT_OTHER_NAME,
     Margin,
     mPadding.mRight,
     eCSSType_Value,

layout/style/nsCSSProps.cpp

@@ -370,6 +370,35 @@ nsCSSProps::GetStringValue(nsCSSFontDesc aFontDescID)
   }
 }
 
+nsCSSProperty
+nsCSSProps::OtherNameFor(nsCSSProperty aProperty)
+{
+  switch (aProperty) {
+    case eCSSProperty_border_left_color_value:
+      return eCSSProperty_border_left_color;
+    case eCSSProperty_border_left_style_value:
+      return eCSSProperty_border_left_style;
+    case eCSSProperty_border_left_width_value:
+      return eCSSProperty_border_left_width;
+    case eCSSProperty_border_right_color_value:
+      return eCSSProperty_border_right_color;
+    case eCSSProperty_border_right_style_value:
+      return eCSSProperty_border_right_style;
+    case eCSSProperty_border_right_width_value:
+      return eCSSProperty_border_right_width;
+    case eCSSProperty_margin_left_value:
+      return eCSSProperty_margin_left;
+    case eCSSProperty_margin_right_value:
+      return eCSSProperty_margin_right;
+    case eCSSProperty_padding_left_value:
+      return eCSSProperty_padding_left;
+    case eCSSProperty_padding_right_value:
+      return eCSSProperty_padding_right;
+    default:
+      NS_ABORT_IF_FALSE(PR_FALSE, "bad caller");
+  }
+  return eCSSProperty_UNKNOWN;
+}
 
 /***************************************************************************/
 

layout/style/nsCSSProps.h

@@ -79,6 +79,13 @@
 // list.
 #define CSS_PROPERTY_IMAGE_IS_IN_ARRAY_0          (1<<6)
 
+// This is a property for which the computed value should generally be
+// reported as the computed value of a property of a different name.  In
+// particular, the directional box properties (margin-left-value, etc.)
+// should be reported as being margin-left, etc.  Call
+// nsCSSProps::OtherNameFor to get the other property.
+#define CSS_PROPERTY_REPORT_OTHER_NAME            (1<<7)
+
 /**
  * Types of animatable values.
  */
@@ -152,6 +159,11 @@ public:
   static const nsAFlatCString& GetStringValue(nsCSSProperty aProperty);
   static const nsAFlatCString& GetStringValue(nsCSSFontDesc aFontDesc);
 
+  // Get the property to report the computed value of aProperty as being
+  // the computed value of.  aProperty must have the
+  // CSS_PROPERTY_REPORT_OTHER_NAME bit set.
+  static nsCSSProperty OtherNameFor(nsCSSProperty aProperty);
+
   // Given a CSS Property and a Property Enum Value
   // Return back a const nsString& representation of the 
   // value. Return back nullstr if no value is found