Compute ids for IR nodes and check equivalence with the AST.

pkg/compiler/lib/src/kernel/kernel_visitor.dart

Index: pkg/compiler/lib/src/kernel/kernel_visitor.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_visitor.dart b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
index f8598a179808c5304ea1a9f2ac3366c75edd5a51..30d1ead5f547bc9a3eb1f6e1838cf4d53c214a95 100644
--- a/pkg/compiler/lib/src/kernel/kernel_visitor.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
@@ -1325,7 +1325,9 @@ class KernelVisitor extends Object
   ir.PropertyGet visitDynamicPropertyGet(
       Send node, Node receiver, Name name, _) {
     return associateNode(
-        new ir.PropertyGet(visitForValue(receiver), nameToIrName(name)), node);
+        new ir.PropertyGet(visitForValue(receiver), nameToIrName(name))
+          ..fileOffset = node.selector.getBeginToken().charOffset,
+        node);
   }
 
   @override
@@ -1333,7 +1335,8 @@ class KernelVisitor extends Object
       Send node, Node receiver, NodeList arguments, Selector selector, _) {
     return associateNode(
         buildInvokeSelector(
-            visitForValue(receiver), selector, buildArguments(arguments)),
+            visitForValue(receiver), selector, buildArguments(arguments))
+          ..fileOffset = node.selector.getBeginToken().charOffset,
         node);
   }