allow createScalerContext to return null, and then have the GDI backend trigger that if we fail to …

src/core/SkGlyphCache.cpp

Index: src/core/SkGlyphCache.cpp
diff --git a/src/core/SkGlyphCache.cpp b/src/core/SkGlyphCache.cpp
index 12e06643fed6434ff1bc6eec9e0e726d7c417a30..d366e1257590f0e1f8e2d405e86fa9af6b986bf1 100644
--- a/src/core/SkGlyphCache.cpp
+++ b/src/core/SkGlyphCache.cpp
@@ -594,13 +594,13 @@ SkGlyphCache* SkGlyphCache::VisitCache(SkTypeface* typeface,
     // If not, we may have exhausted OS/font resources, so try purging the
     // cache once and try again.
     {
-        SkScalerContext* ctx = typeface->createScalerContext(desc);
+        // pass true the first time, to notice if the scalercontext failed,
+        // so we can try the purge.
+        SkScalerContext* ctx = typeface->createScalerContext(desc, true);
         if (!ctx) {
             getSharedGlobals().purgeAll();
-            ctx = typeface->createScalerContext(desc);
-            if (!ctx) {
-                sk_throw();
-            }
+            ctx = typeface->createScalerContext(desc, false);
+            SkASSERT(ctx);
         }
         cache = SkNEW_ARGS(SkGlyphCache, (typeface, desc, ctx));
     }