Bug 1554753 - Should not treat 0 opacity text without stroke width as drawing stroke r=jfkthame

The regressor Bug 1248708 inadvertently changed the behavior for opacity 0 text
when implementing -webkit-text-stroke. It treats all opacity 0 text as drawing stroke
even if the stroke property isn't used in the first place.

We should check aParams.textStrokeWidth is actually set before changing draw mode.

Differential Revision: https://phabricator.services.mozilla.com/D34663

--HG--
extra : moz-landing-system : lando

layout/generic/nsTextFrame.cpp

@@ -6670,7 +6670,8 @@ static void DrawTextRun(const gfxTextRun* aTextRun,
     aParams.callbacks->NotifyAfterText();
   } else {
     auto* textDrawer = aParams.context->GetTextDrawer();
-    if (NS_GET_A(aParams.textColor) != 0 || textDrawer) {
+    if (NS_GET_A(aParams.textColor) != 0 || textDrawer ||
+        aParams.textStrokeWidth == 0.0f) {
       aParams.context->SetColor(Color::FromABGR(aParams.textColor));
     } else {
       params.drawMode = DrawMode::GLYPH_STROKE;