Add support for fields to the new dart backend.

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 cf21ad4c14787ec00f6d7a4bc5e77c78d9f75056..b4b402c383cb7b0d59dda5235275b9f447f60d8b 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
@@ -21,16 +21,28 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
 
   visit(cps_ir.Node node) => node.accept(this);
 
-  void traceGraph(String name, cps_ir.FunctionDefinition graph) {
+  void traceGraph(String name, cps_ir.ExecutableDefinition graph) {
     tag("cfg", () {
       printProperty("name", name);
-      visitFunctionDefinition(graph);
+      visit(graph);
     });
   }
 
   // Temporary field used during tree walk
   Names names;
 
+  visitFieldDefinition(cps_ir.FieldDefinition f) {
+    names = new Names();

[Kevin Millikin (Google), 2014/11/26 13:31:30]

Isn't this the same as the implementation of visitFunctionDefinition?  I don't
care too much for this class, but it might be nice to share the code.

[sigurdm, 2014/11/26 14:38:44]

Done.

+    BlockCollector builder = new BlockCollector(names);
+    builder.visit(f);
+
+    printNode(builder.entry);
+    for (Block block in builder.cont2block.values) {
+      printNode(block);
+    }
+    names = null;
+  }
+
   visitFunctionDefinition(cps_ir.FunctionDefinition f) {
     names = new Names();
     BlockCollector builder = new BlockCollector(names);
@@ -323,6 +335,11 @@ class BlockCollector extends cps_ir.Visitor {
     return block;
   }
 
+  visitFieldDefinition(cps_ir.FieldDefinition f) {

[Kevin Millikin (Google), 2014/11/26 13:31:30]

Same here: you could share the code but I don't care too much one way or the
other :)

[sigurdm, 2014/11/26 14:38:44]

Done.

+    entry = current_block = new Block(names.name(f), [], f.body);
+    visit(f.body);
+  }
+
   visitFunctionDefinition(cps_ir.FunctionDefinition f) {
     entry = current_block = new Block(names.name(f), [], f.body);
     visit(f.body);