Fix test failure by tolerating different line/column numbers.

tools/tests/compiler-plugins.js

@@ -329,8 +329,9 @@ selftest.define("compiler plugins - compiler throws", () => {
   // XXX This is wrong! The path on disk is packages/local-plugin/plugin.js, but
   // at some point we switched to the servePath which is based on the *plugin*'s
   // "package" name.
-  run.matchErr('packages/compilePrintme/plugin.js:5:1: Error in my ' +
-               'registerCompiler callback!');
+  run.matchErr(
+    /packages\/compilePrintme_plugin\.js:\d+:\d+: Error in my registerCompiler callback!/
+  );
   run.expectExit(1);
 });