[svn r71] Fixed accessing parent function arguments from inside nested delegates.

Some cleanups in VarExp::toElem.

test/nested1.d

@@ -0,0 +1,13 @@
+module nested1;
+
+void func(int i)
+{
+    (){
+        assert(i == 3);
+    }();
+}
+
+void main()
+{
+    func(3);
+}

test/nested2.d

@@ -0,0 +1,16 @@
+module nested2;
+
+void func(ref int i)
+{
+    delegate {
+        assert(i == 3);
+        i++;
+    }();
+}
+
+void main()
+{
+    int i = 3;
+    func(i);
+    assert(i == 4);
+}