Fix lingering switch statement test failures.

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 13544295ed919f797916a645838a3cf9185598cd..5f0d3841491c12c4980eb037ca28a36f281b4c49 100644
--- a/pkg/compiler/lib/src/kernel/kernel_visitor.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
@@ -591,7 +591,7 @@ class KernelVisitor extends Object
       // One VariableDefinitions statement node (dart2js AST) may generate
       // multiple statements in Kernel IR so we sometimes fall through here.
     }
-    return new ir.Block(statements);
+    return associateNode(new ir.Block(statements), node);
   }
 
   @override
@@ -826,6 +826,7 @@ class KernelVisitor extends Object
         // its visit method (so it can build break targets correctly).
         ? statement.accept(this)
         : buildStatementInBlock(statement);
+    associateNode(result, statement);
 
     // A [LabeledStatement] isn't the actual jump target, instead, [statement]
     // is the target. This allows uniform handling of break and continue in
@@ -999,7 +1000,8 @@ class KernelVisitor extends Object
     }
     // We ignore the node's statements here, they're generated below in
     // [visitSwitchStatement] once we've set up all the jump targets.
-    return new ir.SwitchCase(expressions, null, isDefault: node.isDefaultCase);
+    return associateNode(new ir.SwitchCase(expressions, null,
+          isDefault: node.isDefaultCase), node);
   }
 
   /// Returns true if [node] would let execution reach the next node (aka