Make block writes in the serializer more efficient.

test/cctest/test-serialize.cc

Index: test/cctest/test-serialize.cc
diff --git a/test/cctest/test-serialize.cc b/test/cctest/test-serialize.cc
index 62c1d8297770b5c8147b203a5c512beea7ed6582..83903e2134a9e53bf02183a7b1db8612c8d64f8c 100644
--- a/test/cctest/test-serialize.cc
+++ b/test/cctest/test-serialize.cc
@@ -1054,7 +1054,7 @@ TEST(SerializeToplevelLargeExternalString) {
   // Create a huge external internalized string to use as variable name.
   Vector<const uint8_t> string =
       ConstructSource(STATIC_CHAR_VECTOR(""), STATIC_CHAR_VECTOR("abcdef"),
-                      STATIC_CHAR_VECTOR(""), 1000000);
+                      STATIC_CHAR_VECTOR(""), 999999);

[vogelheim, 2014/10/23 16:48:44]

What's the significance of this change? Is this meant to trigger the padding
logic, since this string would now require padding?

[Yang, 2014/10/24 07:14:24]

yes.

   Handle<String> name = f->NewStringFromOneByte(string).ToHandleChecked();
   SerializerOneByteResource one_byte_resource(
       reinterpret_cast<const char*>(string.start()), string.length());