Reduction Input:

    ChangeInt32ToFloat64=>          TruncateFloat64ToInt32
                         Float64Mul=>
    ChangeInt32ToFloat64=>          Float64Div=>TruncateFloat64ToInt32

Output:

         =>  TruncateInt64ToInt32
Int64Mul
         =>  Int64Shr => TruncateInt64ToInt32

Test code:

    function mul(a, b) {
      var l = a & 0x3ffffff;
      var h = b & 0x3ffffff;
      var m = l * h;

      var rl = m & 0x3ffffff;
      var rh = (m / 0x4000000) | 0;

      return rl | rh;
    }

    mul(1, 2);
    var a0 = mul(0x3ffffff, 0x3ffffff);
    mul(0x0, 0x0);
    %OptimizeFunctionOnNextCall(mul);
    var a1 = mul(0x3ffffff, 0x3ffffff);

    print(a0 + ' == ' + a1);

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/1350223006

Cr-Commit-Position: refs/heads/master@{#31899}