Eradicate CallSiteInliner::next_ssa_temp_index_.

tests/language/inline_add_constants_to_initial_env.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// Test that SSA values are correctly numbered after inlining that adds constants

[Kevin Millikin (Google), 2012/11/13 00:48:29]

I guess this is a long line.  Suggest // NOLINT or to wrap it.

+// to original environment.
+
+h(x, y) => x == y;
+
+g(y, [x0 = 0, x1 = 1, x2 = 2, x3 = 3]) => y + x0 + x1 + x2 + x3;
+
+f(y) => h(y, g(y));
+
+main() {
+  for (var i = 0; i < 1000; i++) f(i);
+}