Add source information to variable declarations in CPS.

pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
index ec2e34abdace63b8ca0a1f4400d973df757efa13..5e0925458374e3f5df9a8d04c85d89f32b66e9d0 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
@@ -654,10 +654,15 @@ class Unreachable extends Statement {
 class FunctionDefinition extends Node {
   final ExecutableElement element;
   final List<Variable> parameters;
+  final SourceInformation sourceInformation;
   Statement body;
 
   /// Creates a function definition and updates `writeCount` for [parameters].
-  FunctionDefinition(this.element, this.parameters, this.body) {
+  FunctionDefinition(
+      this.element,
+      this.parameters,
+      this.body,
+      {this.sourceInformation}) {
     for (Variable param in parameters) {
       param.writeCount++; // Being a parameter counts as a write.
     }