Set the default whitespace mode to pre-wrap

This CL makes it easier to insert line breaks into text runs.

R=eseidel@chromium.org, eseidel@google.com

Review URL: https://codereview.chromium.org/1221913003.

engine/core/rendering/style/RenderStyle.h

@@ -1029,7 +1029,7 @@ public:
     static EPosition initialPosition() { return StaticPosition; }
     static EUnicodeBidi initialUnicodeBidi() { return UBNormal; }
     static EVisibility initialVisibility() { return VISIBLE; }
-    static EWhiteSpace initialWhiteSpace() { return NORMAL; }
+    static EWhiteSpace initialWhiteSpace() { return PRE_WRAP; }
     static short initialHorizontalBorderSpacing() { return 0; }
     static short initialVerticalBorderSpacing() { return 0; }
     static Color initialColor() { return Color::white; }

tests/widgets/dialog-expected.txt

@@ -13,28 +13,28 @@ PAINT FOR FRAME #2 ----------------------------------------------
 2 |  |  | drawRect(Rect.fromLTRB(0.0, 0.0, 800.0, 600.0), Paint(color:Color(0x7f000000)))
 2 |  | paintChild RenderPositionedBox at Point(0.0, 0.0)
 2 |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  | paintChild RenderPadding at Point(220.0, 206.0)
+2 |  |  | paintChild RenderPadding at Point(220.0, 194.0)
 2 |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  | paintChild RenderConstrainedBox at Point(260.0, 230.0)
+2 |  |  |  | paintChild RenderConstrainedBox at Point(260.0, 218.0)
 2 |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
 2 |  |  |  |  | drawRRect(Instance of 'RRect', Paint(color:Color(0xffffffff), drawLooper:true))
-2 |  |  |  |  | paintChild RenderPadding at Point(260.0, 230.0)
+2 |  |  |  |  | paintChild RenderPadding at Point(260.0, 218.0)
 2 |  |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  |  |  | paintChild RenderParagraph at Point(284.0, 254.0)
+2 |  |  |  |  |  | paintChild RenderParagraph at Point(284.0, 242.0)
 2 |  |  |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  |  |  |  | translate(284.0, 254.0)
-2 |  |  |  |  |  |  | translate(-284.0, -254.0)
-2 |  |  |  |  | paintChild RenderPadding at Point(260.0, 282.0)
+2 |  |  |  |  |  |  | translate(284.0, 242.0)
+2 |  |  |  |  |  |  | translate(-284.0, -242.0)
+2 |  |  |  |  | paintChild RenderPadding at Point(260.0, 270.0)
 2 |  |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  |  |  | paintChild RenderParagraph at Point(284.0, 302.0)
+2 |  |  |  |  |  | paintChild RenderParagraph at Point(284.0, 290.0)
 2 |  |  |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  |  |  |  | translate(284.0, 302.0)
-2 |  |  |  |  |  |  | translate(-284.0, -302.0)
-2 |  |  |  |  | paintChild RenderFlex at Point(260.0, 350.0)
+2 |  |  |  |  |  |  | translate(284.0, 290.0)
+2 |  |  |  |  |  |  | translate(-284.0, -290.0)
+2 |  |  |  |  | paintChild RenderFlex at Point(260.0, 362.0)
 2 |  |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  |  |  | paintChild RenderParagraph at Point(411.0, 350.0)
+2 |  |  |  |  |  | paintChild RenderParagraph at Point(411.0, 362.0)
 2 |  |  |  |  |  |  | TestPaintingCanvas() constructor: 800.0 x 600.0
-2 |  |  |  |  |  |  | translate(411.0, 350.0)
-2 |  |  |  |  |  |  | translate(-411.0, -350.0)
+2 |  |  |  |  |  |  | translate(411.0, 362.0)
+2 |  |  |  |  |  |  | translate(-411.0, -362.0)
 ------------------------------------------------------------------------
 PAINTED 2 FRAMES

tests/widgets/dialog.dart

@@ -13,7 +13,7 @@ main() async {
   await tester.test(() {
     return new Dialog(
       title: new Text("I am a title"),
-      content: new Text("I am some content"),
+      content: new Text("I am some content\nwith a line break"),
       actions: [new Text("I am some actions")]
     );
   });