Refactor handling of source map information.

pkg/compiler/lib/src/ssa/nodes.dart

Index: pkg/compiler/lib/src/ssa/nodes.dart
diff --git a/pkg/compiler/lib/src/ssa/nodes.dart b/pkg/compiler/lib/src/ssa/nodes.dart
index 7337b7b14c7a41568c706f8ce58ad313f60a836d..93f26c1717d9a8a8efe5f9074ea8abc6e864a76d 100644
--- a/pkg/compiler/lib/src/ssa/nodes.dart
+++ b/pkg/compiler/lib/src/ssa/nodes.dart
@@ -759,7 +759,7 @@ class HBasicBlock extends HInstructionList {
 
 abstract class HInstruction implements Spannable {
   Entity sourceElement;
-  SourceFileLocation sourcePosition;
+  SourceInformation sourceInformation;
 
   final int id;
   static int idCounter;
@@ -2882,8 +2882,7 @@ class HLoopBlockInformation implements HStatementInformation {
   final HExpressionInformation updates;
   final JumpTarget target;
   final List<LabelDefinition> labels;
-  final SourceFileLocation sourcePosition;
-  final SourceFileLocation endSourcePosition;
+  final SourceInformation sourceInformation;
 
   HLoopBlockInformation(this.kind,
                         this.initializer,
@@ -2892,8 +2891,7 @@ class HLoopBlockInformation implements HStatementInformation {
                         this.updates,
                         this.target,
                         this.labels,
-                        this.sourcePosition,
-                        this.endSourcePosition) {
+                        this.sourceInformation) {
     assert(
         (kind == DO_WHILE_LOOP ? body.start : condition.start).isLoopHeader());
   }