Bug 1598063 - Don't hide text styled with a pending user font when drawing canvas text, just draw with fallback instead. r=heycam

Differential Revision: https://phabricator.services.mozilla.com/D55707

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

dom/canvas/CanvasRenderingContext2D.cpp

@@ -3493,9 +3493,10 @@ struct MOZ_STACK_CLASS CanvasBidiProcessor
     } else {
       flags &= ~gfx::ShapedTextFlags::TEXT_IS_RTL;
     }
-    mTextRun =
-        mFontgrp->MakeTextRun(aText, aLength, mDrawTarget, mAppUnitsPerDevPixel,
-                              flags, nsTextFrameUtils::Flags(), mMissingFonts);
+    mTextRun = mFontgrp->MakeTextRun(
+        aText, aLength, mDrawTarget, mAppUnitsPerDevPixel, flags,
+        nsTextFrameUtils::Flags::DontSkipDrawingForPendingUserFonts,
+        mMissingFonts);
   }
 
   virtual nscoord GetWidth() override {

gfx/thebes/gfxTextRun.cpp

@@ -183,7 +183,9 @@ gfxTextRun::gfxTextRun(const gfxTextRunFactory::Parameters* aParams,
   AccountStorageForTextRun(this, 1);
 #endif
 
-  mSkipDrawing = mFontGroup->ShouldSkipDrawing();
+  mSkipDrawing =
+      mFontGroup->ShouldSkipDrawing() &&
+      !(aFlags2 & nsTextFrameUtils::Flags::DontSkipDrawingForPendingUserFonts);
 }
 
 gfxTextRun::~gfxTextRun() {

layout/generic/nsTextFrameUtils.h

@@ -35,7 +35,11 @@ class nsTextFrameUtils {
     HasTab = 0x01,
     // the original text has at least one soft hyphen character
     HasShy = 0x02,
-    UnusedFlags = 0x0C,
+    UnusedFlags = 0x04,
+
+    // Flag used in textrun construction to *prevent* hiding of fallback text
+    // for pending user-fonts (used for Canvas2d text).
+    DontSkipDrawingForPendingUserFonts = 0x08,
 
     // The following flags are set by nsTextFrame