Bug 1219833 - Respect composition underline color; r=masayuki

nsTextFrame didn't use the composition underline color if the
composition didn't have a foreground color defined. This patch makes it
use the underline color if foreground color is not defined.

layout/generic/nsTextFrame.cpp

@@ -5407,8 +5407,8 @@ nsTextFrame::DrawSelectionDecorations(gfxContext* aContext,
         // If underline color is defined and that doesn't depend on the
         // foreground color, we should use the color directly.
         if (aRangeStyle.IsUnderlineColorDefined() &&
-            aRangeStyle.IsForegroundColorDefined() &&
-            aRangeStyle.mUnderlineColor != aRangeStyle.mForegroundColor) {
+            (!aRangeStyle.IsForegroundColorDefined() ||
+             aRangeStyle.mUnderlineColor != aRangeStyle.mForegroundColor)) {
           color = aRangeStyle.mUnderlineColor;
         }
         // If foreground color or background color is defined, the both colors