Revert "deps: backport 03ef3cd from V8 upstream"

This reverts commit 6fff47ffac as it is causing
issues in upstream: https://codereview.chromium.org/1390923004/

PR-URL: https://github.com/nodejs/node/pull/3237
Reviewed-By: targos - Michaël Zasso <mic.besace@gmail.com>

deps/v8/src/log.cc

@@ -147,7 +147,7 @@ class CodeEventLogger::NameBuffer {
 
  private:
   static const int kUtf8BufferSize = 512;
-  static const int kUtf16BufferSize = kUtf8BufferSize;
+  static const int kUtf16BufferSize = 128;
 
   int utf8_pos_;
   char utf8_buffer_[kUtf8BufferSize];