Implement simple dynamic type check.

lib/compiler/implementation/ssa/nodes.dart

Index: lib/compiler/implementation/ssa/nodes.dart
diff --git a/lib/compiler/implementation/ssa/nodes.dart b/lib/compiler/implementation/ssa/nodes.dart
index 77dd73313ee2506dd70fb499586b161d113f28d0..01081691fa92151d567a88caefa9cad0a0878ccb 100644
--- a/lib/compiler/implementation/ssa/nodes.dart
+++ b/lib/compiler/implementation/ssa/nodes.dart
@@ -2089,19 +2089,25 @@ class HIndexAssign extends HInvokeStatic {
 }
 
 class HIs extends HInstruction {
-  final Type typeName;
+  final Type typeExpression;

[kasperl, 2012/04/30 08:48:32]

It really isn't an expression but I guess it isn't a name either.

[karlklose, 2012/05/01 11:20:55]

This is actually reverting a renaming from an earlier CL.

   final bool nullOk;
 
-  HIs(this.typeName, HInstruction expression, [nullOk = false])
-    : this.nullOk = nullOk, super(<HInstruction>[expression]);
+  HIs.withTypeInfo(this.typeExpression, HInstruction expression,

[ngeoffray, 2012/04/30 08:51:12]

withTypeInfoCall?

[karlklose, 2012/05/01 11:20:55]

Done.

+                   HInstruction typeInfo, [nullOk = false])

[kasperl, 2012/04/30 08:48:32]

Can't we use this.nullOk in the parameter list?

[karlklose, 2012/05/01 11:20:55]

Done.

+    : this.nullOk = nullOk, super(<HInstruction>[expression, typeInfo]);
+
+  HIs(this.typeExpression, HInstruction expression, [nullOk = false])
+     : this.nullOk = nullOk, super(<HInstruction>[expression]);
 
   HInstruction get expression() => inputs[0];
 
+  HInstruction get typeInfo() => inputs[1];

[ngeoffray, 2012/04/30 08:51:12]

ditto

[karlklose, 2012/05/01 11:20:55]

Done.

+
   HType get guaranteedType() => HType.BOOLEAN;
 
   accept(HVisitor visitor) => visitor.visitIs(this);
 
-  toString() => "$expression is $typeName";
+  toString() => "$expression is $typeExpression";
 }