[wasm] fix loops and if-else to take int type instead of signed

test/mjsunit/regress/regress-617526.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-wasm
+
+// Changing the code a little to avoid infinite loop
+
+function __f_109() {
+  "use asm";
+  function __f_18() {
+    var a = 0;
+    while(2147483648) {
+      a = 1;
+      break;
+    }
+    return a|0;
+  }
+  return {__f_18: __f_18};
+}
+
+var wasm = Wasm.instantiateModuleFromAsm( __f_109.toString());
+assertEquals(1, wasm.__f_18());