Update GrTextBlobCache for DDL

Although, theoretically, we could update the DDLs to maintain pointers to the GrMemoryPools being used by their GrAtlasTextBlobs this method seems simpler.

Change-Id: I4835284630b9cd29eb78cf25bcdfe5c56974a8cb
Reviewed-on: https://skia-review.googlesource.com/107345
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
diff --git a/src/gpu/text/GrAtlasTextBlob.cpp b/src/gpu/text/GrAtlasTextBlob.cpp
index e805761..90bcf5a 100644
--- a/src/gpu/text/GrAtlasTextBlob.cpp
+++ b/src/gpu/text/GrAtlasTextBlob.cpp
@@ -27,7 +27,12 @@
                   glyphCount * sizeof(GrGlyph**) +
                   sizeof(GrAtlasTextBlob::Run) * runCount;
 
-    void* allocation = pool->allocate(size);
+    void* allocation;
+    if (pool) {
+        allocation = pool->allocate(size);
+    } else {
+        allocation = ::operator new (size);
+    }
     if (CACHE_SANITY_CHECK) {
         sk_bzero(allocation, size);
     }