dart2js cps: Store the TypeMask for each primitive in a field.

pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
index 6b56330715f28319ec4b66970c970d96077a4990..47d72f0ddbc3eb6450e30e9fbc802e784c909c98 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
@@ -103,7 +103,8 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
 
   visitLetPrim(cps_ir.LetPrim node) {
     String id = names.name(node.primitive);
-    printStmt(id, "LetPrim $id = ${formatPrimitive(node.primitive)}");
+    String primitive = visit(node.primitive);
+    printStmt(id, "LetPrim $id = $primitive [type=${node.primitive.type}]");
     visit(node.body);
   }
 
@@ -215,7 +216,7 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     String value = formatReference(node.value);
     String args = node.typeArguments.map(formatReference).join(', ');
     String kont = formatReference(node.continuation);
-    printStmt(dummy, "TypeCast ($value ${node.type} ($args)) $kont");
+    printStmt(dummy, "TypeCast ($value ${node.dartType} ($args)) $kont");
   }
 
   visitInvokeContinuation(cps_ir.InvokeContinuation node) {
@@ -249,8 +250,6 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     }
   }
 
-  String formatPrimitive(cps_ir.Primitive p) => visit(p);
-
   visitConstant(cps_ir.Constant node) {
     return "Constant ${node.value.toStructuredString()}";
   }
@@ -344,7 +343,7 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
   visitTypeTest(cps_ir.TypeTest node) {
     String value = formatReference(node.value);
     String args = node.typeArguments.map(formatReference).join(', ');
-    return "TypeTest ($value ${node.type} ($args))";
+    return "TypeTest ($value ${node.dartType} ($args))";
   }
 
   visitApplyBuiltinOperator(cps_ir.ApplyBuiltinOperator node) {