[JS IR] Implement MoveTemporaryVariableDeclarationToAssignment optimization

js/js.translator/testData/js-optimizer/move-temporary-variable-declaration/sameBlock.optimized.js

@@ -0,0 +1,16 @@
+function getArg(x) {
+    return x;
+}
+
+function test(o, k) {
+    var $tmp1 = getArg(k).toUpperCase();
+    var $tmp2 = getArg(o).toUpperCase();
+
+    var O = getArg($tmp2);
+    var K = getArg($tmp1);
+    return O + K;
+}
+
+function box() {
+    return test("o", "k");
+}