check for default typeface for new test

Bug: skia:
Change-Id: I5e52b3259acf73875640ec172d4ff8030975b611
Reviewed-on: https://skia-review.googlesource.com/22262
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/tests/TextBlobTest.cpp b/tests/TextBlobTest.cpp
index 238d734..cec7028 100644
--- a/tests/TextBlobTest.cpp
+++ b/tests/TextBlobTest.cpp
@@ -421,6 +421,12 @@
  *  Then draw the new instance and assert it draws the same as the original.
  */
 DEF_TEST(TextBlob_serialize, reporter) {
+    // test requires at least the default font
+    if (!SkTypeface::MakeDefault()) {
+        SkDebugf("TextBlob_serialize: missing default typeface\n");
+        return;
+    }
+
     SkTextBlobBuilder builder;
 
     sk_sp<SkTypeface> tf0;