Switch SkAutoMalloc to SkAutoTMalloc to avoid cast

tests/Writer32Test.cpp

Index: tests/Writer32Test.cpp
diff --git a/tests/Writer32Test.cpp b/tests/Writer32Test.cpp
index 5849d731efba39ed0e83c82d22ef6a3e8f00ae0c..3fcb64424e5c49b34a852aa4a2783bfd1ee6fdb3 100644
--- a/tests/Writer32Test.cpp
+++ b/tests/Writer32Test.cpp
@@ -144,16 +144,13 @@ static void test2(skiatest::Reporter* reporter, SkWriter32* writer) {
 
 static void testWritePad(skiatest::Reporter* reporter, SkWriter32* writer) {
     // Create some random data to write.
-    const size_t dataSize = 10<<2;
-    SkASSERT(SkIsAlign4(dataSize));
+    const size_t dataSize = 10;
 
-    SkAutoMalloc originalData(dataSize);
+    SkAutoTMalloc<uint32_t> originalData(dataSize);
     {
         SkRandom rand(0);
-        uint32_t* ptr = static_cast<uint32_t*>(originalData.get());
-        uint32_t* stop = ptr + (dataSize>>2);
-        while (ptr < stop) {
-            *ptr++ = rand.nextU();
+        for (size_t i = 0; i < dataSize; i++) {
+            originalData[i] = rand.nextU();
         }
 
         // Write  the random data to the writer at different lengths for