[SkTextBlob] Remove incorrect builder assert

tests/TextBlobTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPaint.h"
 #include "SkPoint.h"
 #include "SkTextBlob.h"
@@ skipping 131 matching lines @@
             REPORTER_ASSERT(reporter, blob->bounds() == SkRect::MakeXYWH(0, 5, 65, 65));
         }
 
         {
             // Verify empty blob bounds after building some non-empty blobs.
             SkAutoTUnref<const SkTextBlob> blob(builder.build());
             REPORTER_ASSERT(reporter, blob->bounds().isEmpty());
         }
 
         // Implicit bounds
-        // FIXME: not supported yet.
+
+        {
+            // Exercise the empty bounds path, and ensure that RunRecord-aligned pos buffers
+            // don't trigger asserts (http://crbug.com/542643).
+            SkPaint p;
+            p.setTextSize(0);
+            p.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
+
+            const char* txt = "BOOO";
+            const size_t len = strlen(txt);
+            const SkTextBlobBuilder::RunBuffer& buffer = builder.allocRunPos(p, (int)len);
+            p.textToGlyphs(txt, len, buffer.glyphs);
+            memset(buffer.pos, 0, sizeof(SkScalar) * len * 2);
+            SkAutoTUnref<const SkTextBlob> blob(builder.build());
+            REPORTER_ASSERT(reporter, blob->bounds().isEmpty());
+        }
     }
 
 private:
     struct RunDef {
         unsigned                     count;
         SkTextBlob::GlyphPositioning pos;
         SkScalar                     x, y;
     };
 
     static void RunBuilderTest(skiatest::Reporter* reporter, SkTextBlobBuilder& builder,
@@ skipping 71 matching lines @@
         default:
             SkFAIL("unhandled positioning value");
         }
     }
 };
 
 DEF_TEST(TextBlob_builder, reporter) {
     TextBlobTester::TestBuilder(reporter);
     TextBlobTester::TestBounds(reporter);
 }