Remove trivial dead stores during dead code elimination
Remove trivial dead stores during dead code elimination

Occasionally this optimizes a StringBuffer into a local string variable.  If we had targeted inlining to inline more methods on StringBuffer we would see more examples.

  padRight: function(source, $length) {
    var result, str, t1;
    result = new P.StringBuffer("");
    str = typeof source === "string" ? source : H.S(source);
    result._contents = str;
    for (t1 = str; t1.length < $length;) {
      t1 += " ";
      result._contents = t1;
    }
    return t1.charCodeAt(0) == 0 ? t1 : t1;
  },

-->

  padRight: function(source, $length) {
    var str, t1;
    str = typeof source === "string" ? source : H.S(source);
    for (t1 = str; t1.length < $length;)
      t1 += " ";
    return t1.charCodeAt(0) == 0 ? t1 : t1;
  },

R=floitsch@google.com

Review URL: https://codereview.chromium.org//780403003

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@42302 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk