Use Dart 2 camel case constants in the engine Dart libraries (#4766)

lib/ui/geometry.dart

@@ -17,16 +17,16 @@ abstract class OffsetBase {
   final double _dx;
   final double _dy;
 
-  /// Returns true if either component is [double.INFINITY], and false if both
+  /// Returns true if either component is [double.infinity], and false if both
   /// are finite (or negative infinity, or NaN).
   ///
   /// This is different than comparing for equality with an instance that has
-  /// _both_ components set to [double.INFINITY].
+  /// _both_ components set to [double.infinity].
   ///
   /// See also:
   ///
   ///  * [isFinite], which is true if both components are finite (and not NaN).
-  bool get isInfinite => _dx >= double.INFINITY || _dy >= double.INFINITY;
+  bool get isInfinite => _dx >= double.infinity || _dy >= double.infinity;
 
   /// Whether both components are finite (neither infinite nor NaN).
   ///
@@ -183,7 +183,7 @@ class Offset extends OffsetBase {
   ///  * [isInfinite], which checks whether either component is infinite.
   ///  * [isFinite], which checks whether both components are finite.
   // This is included for completeness, because [Size.infinite] exists.
-  static const Offset infinite = const Offset(double.INFINITY, double.INFINITY);
+  static const Offset infinite = const Offset(double.infinity, double.infinity);
 
   /// Returns a new offset with the x component scaled by `scaleX` and the y
   /// component scaled by `scaleY`.
@@ -352,10 +352,10 @@ class Size extends OffsetBase {
   const Size.square(double dimension) : super(dimension, dimension);
 
   /// Creates a [Size] with the given [width] and an infinite [height].
-  const Size.fromWidth(double width) : super(width, double.INFINITY);
+  const Size.fromWidth(double width) : super(width, double.infinity);
 
   /// Creates a [Size] with the given [height] and an infinite [width].
-  const Size.fromHeight(double height) : super(double.INFINITY, height);
+  const Size.fromHeight(double height) : super(double.infinity, height);
 
   /// Creates a square [Size] whose [width] and [height] are twice the given
   /// dimension.
@@ -382,7 +382,7 @@ class Size extends OffsetBase {
   ///
   ///  * [isInfinite], which checks whether either dimension is infinite.
   ///  * [isFinite], which checks whether both dimensions are finite.
-  static const Size infinite = const Size(double.INFINITY, double.INFINITY);
+  static const Size infinite = const Size(double.infinity, double.infinity);
 
   /// Whether this size encloses a non-zero area.
   ///
@@ -670,10 +670,10 @@ class Rect {
   /// Whether any of the coordinates of this rectangle are equal to positive infinity.
   // included for consistency with Offset and Size
   bool get isInfinite {
-    return left >= double.INFINITY
-        || top >= double.INFINITY
-        || right >= double.INFINITY
-        || bottom >= double.INFINITY;
+    return left >= double.infinity
+        || top >= double.infinity
+        || right >= double.infinity
+        || bottom >= double.infinity;
   }
 
   /// Whether all coordinates of this rectangle are finite.

lib/ui/hooks.dart

@@ -5,11 +5,11 @@
 part of dart.ui;
 
 String _decodeUTF8(ByteData message) {
-  return message != null ? UTF8.decoder.convert(message.buffer.asUint8List()) : null;
+  return message != null ? utf8.decoder.convert(message.buffer.asUint8List()) : null;
 }
 
 dynamic _decodeJSON(String message) {
-  return message != null ? JSON.decode(message) : null;
+  return message != null ? json.decode(message) : null;
 }
 
 void _updateWindowMetrics(double devicePixelRatio,
@@ -50,8 +50,8 @@ void _updateLocale(String languageCode, String countryCode) {
   _invoke(window.onLocaleChanged, window._onLocaleChangedZone);
 }
 
-void _updateUserSettingsData(String json) {
-  final Map<String, dynamic> data = JSON.decode(json);
+void _updateUserSettingsData(String jsonData) {
+  final Map<String, dynamic> data = json.decode(jsonData);
   _updateTextScaleFactor(data['textScaleFactor'].toDouble());
   _updateAlwaysUse24HourFormat(data['alwaysUse24HourFormat']);
 }
@@ -174,7 +174,7 @@ void _invoke3<A1, A2, A3>(void callback(A1 a1, A2 a2, A3 a3), Zone zone, A1 arg1
 const int _kPointerDataFieldCount = 19;
 
 PointerDataPacket _unpackPointerDataPacket(ByteData packet) {
-  const int kStride = Int64List.BYTES_PER_ELEMENT;
+  const int kStride = Int64List.bytesPerElement;
   const int kBytesPerPointerData = _kPointerDataFieldCount * kStride;
   final int length = packet.lengthInBytes ~/ kBytesPerPointerData;
   assert(length * kBytesPerPointerData == packet.lengthInBytes);

lib/ui/natives.dart

@@ -22,7 +22,7 @@ Future<developer.ServiceExtensionResponse> _scheduleFrame(
   // Schedule the frame.
   window.scheduleFrame();
   // Always succeed.
-  return new developer.ServiceExtensionResponse.result(JSON.encode(<String, String>{
+  return new developer.ServiceExtensionResponse.result(json.encode(<String, String>{
     'type': 'Success',
   }));
 }

lib/ui/painting.dart

@@ -838,9 +838,9 @@ enum PaintingStyle {
 }
 
 // If we actually run on big endian machines, we'll need to do something smarter
-// here. We don't use [Endianness.HOST_ENDIAN] because it's not a compile-time
+// here. We don't use [Endian.Host] because it's not a compile-time
 // constant and can't propagate into the set/get calls.
-const Endianness _kFakeHostEndian = Endianness.LITTLE_ENDIAN;
+const Endian _kFakeHostEndian = Endian.little;
 
 /// A description of the style to use when drawing on a [Canvas].
 ///

lib/ui/pointer.dart

@@ -55,7 +55,7 @@ enum PointerDeviceKind {
 class PointerData {
   /// Creates an object that represents the state of a pointer.
   const PointerData({
-    this.timeStamp: Duration.ZERO,
+    this.timeStamp: Duration.zero,
     this.change: PointerChange.cancel,
     this.kind: PointerDeviceKind.touch,
     this.device: 0,