added front page samples to testing, plus a couple of tweaks to front page and code lab

src/tests/site/code/syntax.dart

-import 'dart:math';                   // Import a library.
+import 'dart:math' show PI;
 
+List shapes = [];                     // Use literals to create lists.
+addShape(shape) => shapes.add(shape); // Function shorthand syntax.
+
+main() {  
+  // The cascade operator (..) saves you from repetitive typing.
+  addShape(new Ellipse(10, 20)..rotation = 45*PI/180
+                              ..color = 'rgb(0,129,198)'
+                              ..outlineWidth = 0);
+  
+  // You can easily insert expression values into strings.
+  print('Area of the first shape: ${shapes[0].area}');
+}
+
 abstract class Shape {

[Kathy Walrath, 2013/11/23 00:46:27]

Why is this still in here?

Oh... I didn't notice that the sample still uses rotation, color, and
outlineWidth, which are defined by Shape.

We should probably change the sample on the page so that class Ellipse extends
Shape.

(We don't need to show Shape.)

   num get area;
   num rotation = 0;
   num outlineWidth = 1;
   String color = 'black';
 }
 
-class Ellipse extends Shape {              // Declare a class.
-  num majorAxis = 0;                       // An instance variable (property).
-  num minorAxis = 0;
+class Ellipse extends Shape {
+  num minorAxis, majorAxis;
+
+  // Syntactic sugar to set members before the constructor body runs.
+  Ellipse(this.minorAxis, this.majorAxis);
+
   static const num C = PI/4;              // A constant.

[Kathy Walrath, 2013/11/23 00:46:27]

Get rid of code that isn't already on the front page (or referred to indirectly
by the front page).

-  num get area => C*majorAxis*minorAxis;   // A property implemented with a getter.
+  num get area => C*majorAxis*minorAxis;  // A property implemented with a getter.

[Kathy Walrath, 2013/11/23 00:46:27]

Should show this on the front page. It seems like there's room, and you refer to
it.

 
-  Ellipse(this.majorAxis, this.minorAxis); // Compact constructor syntax.
-  Ellipse.circle(diameter) {               // A named constructor.
+  Ellipse.circle(diameter) {              // A named constructor.
     minorAxis = majorAxis = diameter;
   }
   
   // Override Object's toString() method.
   String toString() =>
       'Ellipse: ${majorAxis}x${minorAxis} ($area); rotation: $rotation; $color';
 }
-
-// Functions and variables can be inside or outside of classes.
-var shapes = new List();              // A global variable.
-addShape(shape) => shapes.add(shape); // Function shorthand syntax.
-
-// Every app has a main() function, where execution starts.
-main() {  
-  // The cascade operator (..) saves you from repetitive typing.
-  addShape(new Ellipse(10, 20)..rotation = 45*PI/180
-                              ..color = 'rgb(0,129,198)'
-                              ..outlineWidth = 0);
-  
-  // Convert expressions to strings using ${...}.
-  print('Area of the first shape: ${shapes[0].area}');
-  print(shapes[0]);
-}