Update Dart based on dartanalyzer.

Author: Neil Fraser

dart/DMPClass.dart

@@ -1401,7 +1401,7 @@ class DiffMatchPatch {
  param = param.replaceAll('+', '%2B');
  try {
  param = Uri.decodeFull(param);
- } on ArgumentError catch (e) {
+ } on ArgumentError {
  // Malformed URI sequence.
  throw new ArgumentError('Illegal escape in diff_fromDelta: $param');
  }
@@ -1413,7 +1413,7 @@ class DiffMatchPatch {
  int n;
  try {
  n = int.parse(param);
- } on FormatException catch (e) {
+ } on FormatException {
  throw new ArgumentError('Invalid number in diff_fromDelta: $param');
  }
  if (n < 0) {
@@ -1423,7 +1423,7 @@ class DiffMatchPatch {
  String text;
  try {
  text = text1.substring(pointer, pointer += n);
- } on RangeError catch (e) {
+ } on RangeError {
  throw new ArgumentError('Delta length ($pointer)'
  ' larger than source text length (${text1.length}).');
  }
@@ -2163,7 +2163,7 @@ class DiffMatchPatch {
  String line;
  try {
  line = Uri.decodeFull(text[textPointer].substring(1));
- } on ArgumentError catch (e) {
+ } on ArgumentError {
  // Malformed URI sequence.
  throw new ArgumentError('Illegal escape in patch_fromText: $line');
  }

dart/DiffClass.dart

@@ -52,6 +52,19 @@ class Diff {
  * [other] is another Diff to compare against.
  * Returns true or false.
  */
- bool operator ==(Diff other) =>
- operation == other.operation && text == other.text;
+ @override
+ bool operator ==(Object other) =>
+ identical(this, other) ||
+ other is Diff &&
+ runtimeType == other.runtimeType &&
+ operation == other.operation &&
+ text == other.text;
+
+ /**
+ * Generate a uniquely identifiable hashcode for this Diff.
+ * Returns numeric hashcode.
+ */
+ @override
+ int get hashCode =>
+ operation.hashCode ^ text.hashCode;
 }

dart/tests/DiffMatchPatchTest.dart

@@ -16,10 +16,6 @@
  * limitations under the License.
  */
 
-// Can't import DiffMatchPatch library since the private functions would be
-// unavailable. Instead, import all the source files.
-import 'dart:collection';
-import 'dart:math';
 import '../DiffMatchPatch.dart';
 
 // Expect class disappeared from Dart unexpectedly. Here's a minimal shim.
@@ -43,7 +39,7 @@ class Expect {
  static void throws(void f(), String msg) {
  try {
  f();
- } catch (e, s) {
+ } catch (e) {
  return;
  }
  throw new Exception('Expect.throws($msg) fails');