Rename ClosureVariable, use separate IR forms for declaration and assignment.

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 23e6b3bb7f45476018d3bb2af97c162a6901d17e..2fc8597df24155e9dfac334c7c8d856d368fac7e 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
@@ -120,6 +120,12 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     visit(node.body);
   }
 
+  visitLetMutable(cps_ir.LetMutable node) {
+    String id = names.name(node.variable);
+    printStmt(id, "${node.runtimeType} $id = ${formatReference(node.value)}");
+    visit(node.body);
+  }
+
   visitInvokeStatic(cps_ir.InvokeStatic node) {
     String dummy = names.name(node);
     String callName = node.selector.name;
@@ -208,17 +214,17 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     printStmt(dummy, "Branch $condition ($trueCont, $falseCont)");
   }
 
-  visitSetClosureVariable(cps_ir.SetClosureVariable node) {
+  visitSetMutableVariable(cps_ir.SetMutableVariable node) {
     String dummy = names.name(node);
     String variable = names.name(node.variable.definition);
     String value = formatReference(node.value);
-    printStmt(dummy, 'SetClosureVariable $variable = $value');
+    printStmt(dummy, '${node.runtimeType} $variable := $value');
     visit(node.body);
   }
 
   visitDeclareFunction(cps_ir.DeclareFunction node) {
     String dummy = names.name(node);
-    String variable = names.name(node.variable.definition);
+    String variable = names.name(node.variable);
     printStmt(dummy, 'DeclareFunction $variable');
     visit(node.body);
   }
@@ -242,8 +248,8 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     return "Parameter ${names.name(node)}";
   }
 
-  visitClosureVariable(cps_ir.ClosureVariable node) {
-    return "ClosureVariable ${names.name(node)}";
+  visitMutableVariable(cps_ir.MutableVariable node) {
+    return "${node.runtimeType} ${names.name(node)}";
   }
 
   visitContinuation(cps_ir.Continuation node) {
@@ -301,9 +307,9 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     return "CreateFunction ${node.definition.element.name}";
   }
 
-  visitGetClosureVariable(cps_ir.GetClosureVariable node) {
+  visitGetMutableVariable(cps_ir.GetMutableVariable node) {
     String variable = names.name(node.variable.definition);
-    return 'GetClosureVariable $variable';
+    return '${node.runtimeType} $variable';
   }
 
   visitRunnableBody(cps_ir.RunnableBody node) {}
@@ -337,7 +343,7 @@ class Names {
     if (x is cps_ir.Parameter) return 'r';
     if (x is cps_ir.Continuation || x is cps_ir.FunctionDefinition) return 'B';
     if (x is cps_ir.Primitive) return 'v';
-    if (x is cps_ir.ClosureVariable) return 'c';
+    if (x is cps_ir.MutableVariable) return 'c';
     return 'x';
   }
 
@@ -456,7 +462,7 @@ class BlockCollector extends cps_ir.Visitor {
     addEdgeToContinuation(exp.continuation);
   }
 
-  visitSetClosureVariable(cps_ir.SetClosureVariable exp) {
+  visitSetMutableVariable(cps_ir.SetMutableVariable exp) {
     visit(exp.body);
   }