Implement test selection.

tests/corelib/test_config.dart

Index: tests/corelib/test_config.dart
diff --git a/tests/corelib/test_config.dart b/tests/corelib/test_config.dart
index 019ded9e3ebc2f60c3da5b14872f70993a6c8fff..f6839fc400500af5a1ab3c07758c9b77ecfd6c02 100644
--- a/tests/corelib/test_config.dart
+++ b/tests/corelib/test_config.dart
@@ -46,6 +46,14 @@ class CorelibTestSuite {
   void processFile(String filename) {
     if (!filename.endsWith("Test.dart")) return;
 
+    // If patterns are given only list the files that match one of the
+    // patterns.
+    var patterns = configuration['patterns'];
+    if (!patterns.isEmpty() &&
+        !patterns.some((re) => re.hasMatch(filename))) {
+      return;
+    }
+
     int start = filename.lastIndexOf(pathSeparator);
     String testName = filename.substring(start + 1, filename.length - 5);
     Set<String> expectations = testExpectationsMap.expectations(testName);