--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -4797,18 +4797,26 @@ nsDisplayText::Paint(nsDisplayListBuilde
       gfxMatrix mat = ctx->CurrentMatrix()
         .Translate(pt).Scale(scaleFactor, 1.0).Translate(-pt);
       ctx->SetMatrix(mat);
     }
   }
   nsTextFrame::PaintTextParams params(aCtx->ThebesContext());
   params.framePt = gfxPoint(framePt.x, framePt.y);
   params.dirtyRect = extraVisible;
-  params.generateTextMask = aBuilder->IsForGenerateGlyphMask();
-  params.paintSelectionBackground = aBuilder->IsForPaintingSelectionBG();
+
+  if (aBuilder->IsForGenerateGlyphMask()) {
+    MOZ_ASSERT(!aBuilder->IsForPaintingSelectionBG());
+    params.state = nsTextFrame::PaintTextParams::GenerateTextMask;
+  } else if (aBuilder->IsForPaintingSelectionBG()) {
+    params.state = nsTextFrame::PaintTextParams::PaintTextBGColor;
+  } else {
+    params.state = nsTextFrame::PaintTextParams::PaintText;
+  }
+
   f->PaintText(params, *this, mOpacity);
 }
 
 void
 nsTextFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                               const nsRect&           aDirtyRect,
                               const nsDisplayListSet& aLists)
 {
@@ -5998,18 +6006,17 @@ nsTextFrame::PaintTextWithSelectionColor
   bool vertical = mTextRun->IsVertical();
   const gfxFloat startIOffset = vertical ?
     aParams.textBaselinePt.y - aParams.framePt.y :
     aParams.textBaselinePt.x - aParams.framePt.x;
   gfxFloat iOffset, hyphenWidth;
   Range range; // in transformed string
   TextRangeStyle rangeStyle;
   // Draw background colors
-  if (anyBackgrounds && (!aParams.generateTextMask ||
-                         aParams.paintSelectionBackground)) {
+  if (anyBackgrounds && !aParams.IsGenerateTextMask()) {
     int32_t appUnitsPerDevPixel =
       aParams.textPaintStyle->PresContext()->AppUnitsPerDevPixel();
     SelectionIterator iterator(prevailingSelections, contentRange,
                                *aParams.provider, mTextRun, startIOffset);
     SelectionType selectionType;
     while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
                                    &selectionType, &rangeStyle)) {
       nscolor foreground, background;
@@ -6032,17 +6039,17 @@ nsTextFrame::PaintTextWithSelectionColor
           *aParams.context->GetDrawTarget(), background, aParams.dirtyRect,
           LayoutDeviceRect::FromAppUnits(bgRect, appUnitsPerDevPixel),
           aParams.callbacks);
       }
       iterator.UpdateWithAdvance(advance);
     }
   }
 
-  if (aParams.paintSelectionBackground) {
+  if (aParams.IsPaintBGColor()) {
     return true;
   }
 
   gfxFloat advance;
   DrawTextParams params(aParams.context);
   params.dirtyRect = aParams.dirtyRect;
   params.framePt = aParams.framePt;
   params.provider = aParams.provider;
@@ -6058,17 +6065,17 @@ nsTextFrame::PaintTextWithSelectionColor
   // Draw text
   const nsStyleText* textStyle = StyleText();
   SelectionIterator iterator(prevailingSelections, contentRange,
                              *aParams.provider, mTextRun, startIOffset);
   SelectionType selectionType;
   while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
                                  &selectionType, &rangeStyle)) {
     nscolor foreground, background;
-    if (aParams.generateTextMask) {
+    if (aParams.IsGenerateTextMask()) {
       foreground = NS_RGBA(0, 0, 0, 255);
     } else {
       GetSelectionTextColors(selectionType, *aParams.textPaintStyle,
                              rangeStyle, &foreground, &background);
     }
 
     gfxPoint textBaselinePt = vertical ?
       gfxPoint(aParams.textBaselinePt.x, aParams.framePt.y + iOffset) :
@@ -6591,57 +6598,56 @@ nsTextFrame::PaintText(const PaintTextPa
   }
   nsCharClipDisplayItem::ClipEdges clipEdges(aItem, snappedStartEdge,
                                              snappedEndEdge);
   nsTextPaintStyle textPaintStyle(this);
   textPaintStyle.SetResolveColors(!aParams.callbacks);
 
   // Fork off to the (slower) paint-with-selection path if necessary.
   if (aItem.mIsFrameSelected.value() &&
-      (aParams.paintSelectionBackground ||
-       ShouldDrawSelection(this->GetParent()))) {
+      (aParams.IsPaintBGColor() || ShouldDrawSelection(this->GetParent()))) {
     MOZ_ASSERT(aOpacity == 1.0f, "We don't support opacity with selections!");
     gfxSkipCharsIterator tmp(provider.GetStart());
     Range contentRange(
       uint32_t(tmp.ConvertSkippedToOriginal(startOffset)),
       uint32_t(tmp.ConvertSkippedToOriginal(startOffset + maxLength)));
     PaintTextSelectionParams params(aParams);
     params.textBaselinePt = textBaselinePt;
     params.provider = &provider;
     params.contentRange = contentRange;
     params.textPaintStyle = &textPaintStyle;
     if (PaintTextWithSelection(params, clipEdges)) {
       return;
     }
   }
 
-  if (aParams.paintSelectionBackground) {
+  if (aParams.IsPaintBGColor()) {
     return;
   }
 
-  nscolor foregroundColor = aParams.generateTextMask
+  nscolor foregroundColor = aParams.IsGenerateTextMask()
                             ? NS_RGBA(0, 0, 0, 255)
                             : textPaintStyle.GetTextColor();
   if (aOpacity != 1.0f) {
     gfx::Color gfxColor = gfx::Color::FromABGR(foregroundColor);
     gfxColor.a *= aOpacity;
     foregroundColor = gfxColor.ToABGR();
   }
 
-  nscolor textStrokeColor = aParams.generateTextMask
+  nscolor textStrokeColor = aParams.IsGenerateTextMask()
                             ? NS_RGBA(0, 0, 0, 255)
                             : textPaintStyle.GetWebkitTextStrokeColor();
   if (aOpacity != 1.0f) {
     gfx::Color gfxColor = gfx::Color::FromABGR(textStrokeColor);
     gfxColor.a *= aOpacity;
     textStrokeColor = gfxColor.ToABGR();
   }
 
   range = Range(startOffset, startOffset + maxLength);
-  if (!aParams.callbacks && !aParams.generateTextMask) {
+  if (!aParams.callbacks && aParams.IsPaintText()) {
     const nsStyleText* textStyle = StyleText();
     PaintShadowParams shadowParams(aParams);
     shadowParams.range = range;
     shadowParams.textBaselinePt = textBaselinePt;
     shadowParams.leftSideOffset = snappedStartEdge;
     shadowParams.provider = &provider;
     shadowParams.foregroundColor = foregroundColor;
     shadowParams.clipEdges = &clipEdges;

--- a/layout/generic/nsTextFrame.h
+++ b/layout/generic/nsTextFrame.h
@@ -390,19 +390,31 @@ public:
 
   struct PaintTextParams
   {
     gfxContext* context;
     gfxPoint framePt;
     LayoutDeviceRect dirtyRect;
     gfxTextContextPaint* contextPaint = nullptr;
     DrawPathCallbacks* callbacks = nullptr;
-    bool generateTextMask = false;
-    bool paintSelectionBackground = false;
+    enum {
+      PaintText,           // Normal text painting.
+      PaintTextBGColor,    // Only paint background color of the selected text
+                           // range in this state.
+      GenerateTextMask     // To generate a mask from a text frame. Should
+                           // only paint text itself with opaque color.
+                           // Text shadow, text selection color and text
+                           // decoration are all discarded in this state.
+    };
+    uint8_t state = PaintText;
     explicit PaintTextParams(gfxContext* aContext) : context(aContext) {}
+
+    bool IsPaintText() const { return state == PaintText; }
+    bool IsGenerateTextMask() const { return state == GenerateTextMask; }
+    bool IsPaintBGColor() const { return state == PaintTextBGColor; }
   };
 
   struct PaintTextSelectionParams : PaintTextParams
   {
     gfxPoint textBaselinePt;
     PropertyProvider* provider = nullptr;
     Range contentRange;
     nsTextPaintStyle* textPaintStyle = nullptr;