Use Representation::Integer32() for smi types on 32-bit-tagged systems.

test/mjsunit/regress/regress-crbug-349079.js

Index: test/mjsunit/regress/regress-crbug-349079.js
diff --git a/test/mjsunit/regress/regress-crbug-349079.js b/test/mjsunit/regress/regress-crbug-349079.js
index b1076ea435c7d1e66c7bb906bf718b1ba1dc2a7b..822941ae08d80fbe0f292370206f406e44b49987 100644
--- a/test/mjsunit/regress/regress-crbug-349079.js
+++ b/test/mjsunit/regress/regress-crbug-349079.js
@@ -21,3 +21,16 @@ crash();
 crash();
 %OptimizeFunctionOnNextCall(crash);
 crash();
+
+function f() {
+  var v1 = 0;
+  var v2 = -0;
+  var t = v2++;
+  v2++;
+  return Math.max(v2++, v1++);
+}
+
+f();
+f();
+%OptimizeFunctionOnNextCall(f);
+f();