Better syntax highlighting for Dart (#1959)

Remove unmaintained Dart syntax submodule. Add elMuso/Dartlight as submodule. Update Dart syntax highlighting. Add changes to changelog.

tests/syntax-tests/highlighted/Dart/inner_comment.dart

@@ -0,0 +1,5 @@
+return Object(
+  Object(
+    // Not highlighted as a comment
+  )
+)

tests/syntax-tests/highlighted/Dart/test.dart

@@ -1,45 +1,45 @@
 /* array sorting alogorithm */
-int partition(List list, int low, int high) {
-  if (list == null || list.length == 0) return 0;
-  int pivot = list[high];
-  int i = low - 1;
+int partition(List list, int low, int high) {
+  if (list == null || list.length == 0) return 0;
+  int pivot = list[high];
+  int i = low - 1;
 
-  void swap(List list, int i, int j) {
-    int temp = list[i];
+  void swap(List list, int i, int j) {
+    int temp = list[i];
     list[i] = list[j];
     list[j] = temp;
   }
 
-  for (int j = low; j < high; j++) {
+  for (int j = low; j < high; j++) {
     if (list[j] <= pivot) {
       i++;
-      swap(list, i, j);
+      swap(list, i, j);
     }
-    swap(list, i + 1, high);
+    swap(list, i + 1, high);
     return i + 1;
   }
 }
 
-void quickSort(List list, int low, int high) {
+void quickSort(List list, int low, int high) {
   if (low < high) {
-    int pi = partition(list, low, high);
-    quickSort(list, low, pi - 1);
-    quickSort(list, pi + 1, high);
+    int pi = partition(list, low, high);
+    quickSort(list, low, pi - 1);
+    quickSort(list, pi + 1, high);
   }
 }
 
-void merge(List list, int leftIndex, int middleIndex, int rightIndex) {
-  int leftSize = middleIndex - leftIndex + 1;
-  int rightSize = rightIndex - middleIndex;
+void merge(List list, int leftIndex, int middleIndex, int rightIndex) {
+  int leftSize = middleIndex - leftIndex + 1;
+  int rightSize = rightIndex - middleIndex;
 
-  List leftList = new List(leftSize);
-  List rightList = new List(rightSize);
+  List leftList = new List(leftSize);
+  List rightList = new List(rightSize);
 
-  for (int i = 0; i < leftSize; i++) leftList[i] = list[leftIndex + i];
-  for (int j = 0; j < rightSize; j++) rightList[j] = list[middleIndex + j + 1];
+  for (int i = 0; i < leftSize; i++) leftList[i] = list[leftIndex + i];
+  for (int j = 0; j < rightSize; j++) rightList[j] = list[middleIndex + j + 1];
 
-  int i = 0, j = 0;
-  int k = leftIndex;
+  int i = 0, j = 0;
+  int k = leftIndex;
 
   while (i < leftSize && j < rightSize) {
     if (leftList[i] <= rightList[j]) {
@@ -65,14 +65,14 @@
   }
 }
 
-void mergeSort(List list, int leftIndex, int rightIndex) {
+void mergeSort(List list, int leftIndex, int rightIndex) {
   if (leftIndex < rightIndex) {
-    int middleIndex = (rightIndex + leftIndex) ~/ 2;
+    int middleIndex = (rightIndex + leftIndex) ~/ 2;
 
-    mergeSort(list, leftIndex, middleIndex);
-    mergeSort(list, middleIndex + 1, rightIndex);
+    mergeSort(list, leftIndex, middleIndex);
+    mergeSort(list, middleIndex + 1, rightIndex);
 
-    merge(list, leftIndex, middleIndex, rightIndex);
+    merge(list, leftIndex, middleIndex, rightIndex);
   }
 }
 
@@ -80,54 +80,54 @@
 var name = 'Voyager I';
 var year = 1977;
 var antennaDiameter = 3.7;
-var flybyObjects = ['Jupiter', 'Saturn', 'Uranus', 'Neptune'];
+var flybyObjects = ['Jupiter', 'Saturn', 'Uranus', 'Neptune'];
 var image = {
-  'tags': ['saturn'],
-  'url': '//path/to/saturn.jpg'
+  'tags': ['saturn'],
+  'url': '//path/to/saturn.jpg'
 };
 
 /*classes */
-class Spacecraft {
-  String name;
-  DateTime launchDate;
-  Spacecraft(this.name, this.launchDate) {}
+class Spacecraft {
+  String name;
+  DateTime launchDate;
+  Spacecraft(this.name, this.launchDate) {}
 
-  // Named constructor that forwards to the default one.
-  Spacecraft.unlaunched(String name) : this(name, null);
+  // Named constructor that forwards to the default one.
+  Spacecraft.unlaunched(String name) : this(name, null);
 
-  int get launchYear => launchDate?.year;
+  int get launchYear => launchDate?.year;
 
-  void describe() {
-    print('Spacecraft: $name');
+  void describe() {
+    print('Spacecraft: $name');
     if (launchDate != null) {
-      int years = DateTime.now().difference(launchDate).inDays ~/ 365;
-      print('Launched: $launchYear ($years years ago)');
+      int years = DateTime.now().difference(launchDate).inDays ~/ 365;
+      print('Launched: $launchYear ($years years ago)');
     } else {
-      print('Unlaunched');
+      print('Unlaunched');
     }
   }
 }
 
 /* Mixins */
-class PilotedCraft extends Spacecraft with Piloted {
-  // ···
+class PilotedCraft extends Spacecraft with Piloted {
+  // ···
 }
 
 /* Interfaces and abstract classes */
-class MockSpaceship implements Spacecraft {
-  // ···
+class MockSpaceship implements Spacecraft {
+  // ···
 }
 
 /* async */
-Future<void> printWithDelay(String message) {
-  return Future.delayed(const Duration(seconds: 2)).then((_) {
-    print(message);
+Future<void> printWithDelay(String message) {
+  return Future.delayed(const Duration(seconds: 2)).then((_) {
+    print(message);
   });
 }
 
-Stream<String> report(Spacecraft craft, Iterable<String> objects) async* {
+Stream<String> report(Spacecraft craft, Iterable<String> objects) async* {
   for (var object in objects) {
-    await Future.delayed(const Duration(seconds: 2));
-    yield '${craft.name} flies by $object';
+    await Future.delayed(const Duration(seconds: 2));
+    yield '${craft.name} flies by $object';
   }
 }

tests/syntax-tests/source/Dart/inner_comment.dart

@@ -0,0 +1,5 @@
+return Object(
+  Object(
+    // Not highlighted as a comment
+  )
+)