Update comment to provide the correct usage of the Disassembler class.

TBR=erik.corry@gmail.com
Review URL: http://codereview.chromium.org/1755001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4457 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/disasm-arm.cc

@@ -34,10 +34,9 @@
 //   NameConverter converter;
 //   Disassembler d(converter);
 //   for (byte* pc = begin; pc < end;) {
-//     char buffer[128];
-//     buffer[0] = '\0';
+//     v8::internal::EmbeddedVector<char, 256> buffer;
 //     byte* prev_pc = pc;
-//     pc += d.InstructionDecode(buffer, sizeof buffer, pc);
+//     pc += d.InstructionDecode(buffer, pc);
 //     printf("%p    %08x      %s\n",
 //            prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer);
 //   }