[JS IR] Drop TemporaryAssignmentElimination optimization

Enable TemporaryAssignment tests

js/js.translator/testData/js-optimizer/temporary-assignment/assignment.optimized.js

@@ -1,11 +1,12 @@
 function test(n) {
     var result;
+    var $tmp;
     if (n >= 0) {
-        result = n;
-    }
-    else {
-        result = -n;
+        $tmp = n;
+    } else {
+        $tmp = -n;
     }
+    result = $tmp;
     return result;
 }
 
@@ -17,4 +18,4 @@ function box() {
     if (result != 20) return "fail2: " + result;
 
     return "OK"
-}
+}