Fix test.dart to have the same behavior as test.py for --frog and --froglib.

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
===================================================================
--- tools/testing/dart/test_suite.dart	(revision 3364)
+++ tools/testing/dart/test_suite.dart	(working copy)
@@ -444,7 +444,11 @@
           break;
         case 'frogium':
         case 'webdriver':
-          compilerArgs.addAll(['--libdir=$dartDir/frog/lib',
+          String libdir = configuration['froglib'];
+          if (libdir == '') {
+            libdir = '$dartDir/frog/lib';
+          }
+          compilerArgs.addAll(['--libdir=$libdir',
                                '--compile-only',
                                '--out=$compiledDartWrapperFilename']);
           compilerArgs.addAll(vmOptions);
@@ -462,6 +466,7 @@
       String executable = getFilename(dumpRenderTreeFilename);
       List<String> args;
       if (component == 'webdriver') {
+        // TODO(efortuna): These paths are not OS independent! 
         executable = '$dartDir/tools/testing/run_selenium.py';
         args = ['--out', htmlPath, '--browser', configuration['browser']];
       } else {
@@ -928,7 +933,10 @@
     if (configuration['component'] == 'dartium') {
       return null;  // No separate compiler for dartium tests.
     }
-    var name = '${buildDir(configuration)}/${compilerName(configuration)}';
+    var name = configuration['frog'];

[Bill Hesse, 2012/01/19 16:31:28]

I don't think we want --frog to override the dartc path if component =
'chromium' or 'dartc'.  This could happen with
test.dart -cchromium,frogium --frog=i_built/this/frogsh.
Could this be
if (configuration['frog'] != '' && (configuration['component'] == 'frogium' ||
... 'webkit')) {
 name = configuration['frog'];
} else {
 name = ....
}

+    if (name == '') {
+      name = '${buildDir(configuration)}/${compilerName(configuration)}';
+    }
     if (!(new File(name)).existsSync()) {
       throw "Executable '$name' does not exist";
     }