Make source information on conditions mandatory in CPS

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

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library dart2js.ir_nodes;
 
 import 'dart:collection';
 import 'cps_fragment.dart' show CpsFragment;
 import 'cps_ir_nodes_sexpr.dart';
 import '../constants/values.dart' as values;
 import '../dart_types.dart' show DartType, InterfaceType, TypeVariableType;
@@ skipping 2054 matching lines @@
   }
 }
 
 /// Choose between a pair of continuations based on a condition value.
 ///
 /// The two continuations must not declare any parameters.
 class Branch extends TailExpression {
   final Reference<Primitive> conditionRef;
   final Reference<Continuation> trueContinuationRef;
   final Reference<Continuation> falseContinuationRef;
+  final SourceInformation sourceInformation;
 
   Primitive get condition => conditionRef.definition;
   Continuation get trueContinuation => trueContinuationRef.definition;
   Continuation get falseContinuation => falseContinuationRef.definition;
 
   /// If true, only the value `true` satisfies the condition. Otherwise, any
   /// truthy value satisfies the check.
   ///
   /// Non-strict checks are preferable when the condition is known to be a
   /// boolean.
   bool isStrictCheck;
 
-  Branch(Primitive condition, Continuation trueCont, Continuation falseCont,
+  Branch(
+      Primitive condition,
+      Continuation trueCont,
+      Continuation falseCont,
+      this.sourceInformation,
       {bool strict})
       : this.conditionRef = new Reference<Primitive>(condition),
         trueContinuationRef = new Reference<Continuation>(trueCont),
         falseContinuationRef = new Reference<Continuation>(falseCont),
         isStrictCheck = strict {
     assert(strict != null);
   }
 
   Branch.strict(
-      Primitive condition, Continuation trueCont, Continuation falseCont)
-      : this(condition, trueCont, falseCont, strict: true);
+      Primitive condition,
+      Continuation trueCont,
+      Continuation falseCont,
+      SourceInformation sourceInformation)
+      : this(condition, trueCont, falseCont, sourceInformation, strict: true);
 
   Branch.loose(
-      Primitive condition, Continuation trueCont, Continuation falseCont)
-      : this(condition, trueCont, falseCont, strict: false);
+      Primitive condition,
+      Continuation trueCont,
+      Continuation falseCont,
+      SourceInformation sourceInformation)
+      : this(condition, trueCont, falseCont, sourceInformation, strict: false);
 
   accept(BlockVisitor visitor) => visitor.visitBranch(this);
 
   void setParentPointers() {
     conditionRef.parent = this;
     trueContinuationRef.parent = this;
     falseContinuationRef.parent = this;
   }
 }
 
@@ skipping 1014 matching lines @@
   }
 
   visitRethrow(Rethrow node) {
     plug(new Rethrow());
   }
 
   visitBranch(Branch node) {
     plug(new Branch.loose(
         _definitions.getCopy(node.conditionRef),
         _copies[node.trueContinuation],
-        _copies[node.falseContinuation])..isStrictCheck = node.isStrictCheck);
+        _copies[node.falseContinuation],
+        node.sourceInformation)..isStrictCheck = node.isStrictCheck);
   }
 
   visitUnreachable(Unreachable node) {
     plug(new Unreachable());
   }
 }