Validate patch file paths.

pkg/analyzer/test/src/dart/sdk/sdk_test.dart

Index: pkg/analyzer/test/src/dart/sdk/sdk_test.dart
diff --git a/pkg/analyzer/test/src/dart/sdk/sdk_test.dart b/pkg/analyzer/test/src/dart/sdk/sdk_test.dart
index 214bfa224dc59f06c7b621261b1064e24aa0c6fb..e684880503037e1f658d216c00e76978ebc5317a 100644
--- a/pkg/analyzer/test/src/dart/sdk/sdk_test.dart
+++ b/pkg/analyzer/test/src/dart/sdk/sdk_test.dart
@@ -527,6 +527,21 @@ final Map<String, LibraryInfo> LIBRARIES = const <String, LibraryInfo> {
     }, throwsArgumentError);
   }
 
+  void test_readFrom_patches_invalid_path_hasDotDot() {
+    _assertPathIsInvalid('foo/../bar.dart');
+    _assertPathIsInvalid('../foo/bar.dart');
+    _assertPathIsInvalid('foo/bar..dart');
+  }
+
+  void test_readFrom_patches_invalid_path_isAbsolute() {
+    _assertPathIsInvalid('/foo.dart');
+    _assertPathIsInvalid('/foo/bar.dart');
+  }
+
+  void test_readFrom_patches_invalid_path_notPosix() {
+    _assertPathIsInvalid(r'foo\bar.dart');
+  }
+
   void test_readFrom_patches_invalid_platformCombinator() {
     expect(() {
       new SdkLibrariesReader(false).readFromFile(
@@ -571,6 +586,20 @@ final Map<String, LibraryInfo> LIBRARIES = const <String, LibraryInfo> {
     expect(library.getPatches(SdkLibraryImpl.VM_PLATFORM), isEmpty);
     expect(library.getPatches(SdkLibraryImpl.DART2JS_PLATFORM), isEmpty);
   }
+
+  void _assertPathIsInvalid(String patchPath) {
+    expect(() {
+      new SdkLibrariesReader(false).readFromFile(
+          resourceProvider.getFile('/libs.dart'),
+          '''
+final Map<String, LibraryInfo> LIBRARIES = const <String, LibraryInfo> {
+  'foo' : const LibraryInfo(
+    'foo/foo.dart',
+    patches: {
+      VM_PLATFORM: [r'$patchPath']}),
+};''');
+    }, throwsArgumentError);
+  }
 }
 
 @reflectiveTest