Adding support checks for FileSystem APIs and making APIs not webkit-specific.

tests/html/fileapi_test.dart

 library fileapi;
 import '../../pkg/unittest/lib/unittest.dart';
-import '../../pkg/unittest/lib/html_config.dart';
+import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
 void fail(message) {
   guardAsync(() {
     expect(false, isTrue, reason: message);
   });
 }
 
 FileSystem fs;
 
 main() {
-  useHtmlConfiguration();
-  test('getFileSystem', () {
-    window.webkitRequestFileSystem(Window.TEMPORARY, 100, expectAsync1(
-      (FileSystem fileSystem) {
-        fs = fileSystem;
-      }),
-      (e) {
-        fail('Got file error: ${e.code}');
-      });
-  });
-  group('getDirectory', () {
+  useHtmlIndividualConfiguration();
 
-    test('directoryDoesntExist', () {
-      fs.root.getDirectory(
-          'directory2',
-          options: {},
-          successCallback: (e) {
-            fail('Should not be reached');
-          },
-          errorCallback: expectAsync1((FileError e) {
-            expect(e.code, equals(FileError.NOT_FOUND_ERR));
-          }));
-    });
-
-    test('directoryCreate', () {
-      fs.root.getDirectory(
-          'directory3',
-          options: {'create': true},
-          successCallback: expectAsync1((DirectoryEntry e) {
-            expect(e.name, equals('directory3'));
-          }),
-          errorCallback: (e) {
-            fail('Got file error: ${e.code}');
-          });
+  group('supported', () {
+    test('supported', () {
+      expect(FileSystem.supported, true);
     });
   });
 
+  getFileSystem() {
+    window.requestFileSystem(Window.TEMPORARY, 100,
+        expectAsync1((FileSystem fileSystem) {
+          fs = fileSystem;
+        }),
+        (e) {
+          fail('Got file error: ${e.code}');
+        });
+  }
+
+  group('fileSystem', () {
+    test('getFileSystem', () {
+      var expectation = FileSystem.supported ? returnsNormally : throws;
+      expect(() {
+        getFileSystem();
+      }, expectation);
+    });
+  });
+
+  group('getDirectory', () {
+    if (FileSystem.supported) {
+      test('getFileSystem', getFileSystem);
+
+      test('directoryDoesntExist', () {
+        fs.root.getDirectory(
+            'directory2',
+            options: {},
+            successCallback: (e) {
+              fail('Should not be reached');
+            },
+            errorCallback: expectAsync1((FileError e) {
+              expect(e.code, equals(FileError.NOT_FOUND_ERR));
+            }));
+        });
+
+      test('directoryCreate', () {
+        fs.root.getDirectory(
+            'directory3',
+            options: {'create': true},
+            successCallback: expectAsync1((DirectoryEntry e) {
+              expect(e.name, equals('directory3'));
+            }),
+            errorCallback: (e) {
+              fail('Got file error: ${e.code}');
+            });
+        });
+    }
+  });
+
   group('getFile', () {
+    if (FileSystem.supported) {
+      test('getFileSystem', getFileSystem);
 
-    test('fileDoesntExist', () {
-      fs.root.getFile(
-          'file2',
-          options: {},
-          successCallback: (e) {
-            fail('Should not be reached');
-          },
-          errorCallback: expectAsync1((FileError e) {
-            expect(e.code, equals(FileError.NOT_FOUND_ERR));
-          }));
-    });
+      test('fileDoesntExist', () {
+        fs.root.getFile(
+            'file2',
+            options: {},
+            successCallback: (e) {
+              fail('Should not be reached');
+            },
+            errorCallback: expectAsync1((FileError e) {
+              expect(e.code, equals(FileError.NOT_FOUND_ERR));
+            }));
+      });
 
-    test('fileCreate', () {
-      fs.root.getFile(
-          'file4',
-          options: {'create': true},
-          successCallback: expectAsync1((FileEntry e) {
-            expect(e.name, equals('file4'));
-            expect(e.isFile, isTrue);
-          }),
-          errorCallback: (e) {
-            fail('Got file error: ${e.code}');
-          });
-      });
+      test('fileCreate', () {
+        fs.root.getFile(
+            'file4',
+            options: {'create': true},
+            successCallback: expectAsync1((FileEntry e) {
+              expect(e.name, equals('file4'));
+              expect(e.isFile, isTrue);
+            }),
+            errorCallback: (e) {
+              fail('Got file error: ${e.code}');
+            });
+        });
+    }
   });
 }