Fix SkFixedDiv macro

tests/MathTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "float.h"
 
 #include "SkColorPriv.h"
@@ skipping 512 matching lines @@
                     (SkScalar) (rand.nextS() >> 13),
                     SK_Scalar1);
         check_length(reporter, p, SK_Scalar1);
     }
 
     {
         SkFixed result = SkFixedDiv(100, 100);
         REPORTER_ASSERT(reporter, result == SK_Fixed1);
         result = SkFixedDiv(1, SK_Fixed1);
         REPORTER_ASSERT(reporter, result == 1);
+        result = SkFixedDiv(10 - 1, SK_Fixed1 * 3);
+        REPORTER_ASSERT(reporter, result == 3);
     }
 
     unittest_fastfloat(reporter);
     unittest_isfinite(reporter);
     unittest_half(reporter);
     test_rsqrt(reporter, sk_float_rsqrt);
     test_rsqrt(reporter, sk_float_rsqrt_portable);
 
     for (i = 0; i < 10000; i++) {
         SkFixed numer = rand.nextS();
@@ skipping 127 matching lines @@
     test_divmod<int16_t>(r);
 }
 
 DEF_TEST(divmod_s32, r) {
     test_divmod<int32_t>(r);
 }
 
 DEF_TEST(divmod_s64, r) {
     test_divmod<int64_t>(r);
 }