Give instances their own model class; move DartErrors out of instance-ref into their own error-ref.

runtime/bin/vmservice/observatory/deployed/web/index.html._data

Index: runtime/bin/vmservice/observatory/deployed/web/index.html._data
diff --git a/runtime/bin/vmservice/observatory/deployed/web/index.html._data b/runtime/bin/vmservice/observatory/deployed/web/index.html._data
index ad05463f7eeb3827e7a4b61502f6b607c66f7648..6e6bdc5aa73d1945f12477fe66e82dbf9cb8c877 100644
--- a/runtime/bin/vmservice/observatory/deployed/web/index.html._data
+++ b/runtime/bin/vmservice/observatory/deployed/web/index.html._data
@@ -1 +1 @@
-{"experimental_bootstrap":false,"script_ids":[["observatory","lib/src/elements/curly_block.dart"],["observatory","lib/src/elements/observatory_element.dart"],["observatory","lib/src/elements/service_ref.dart"],["observatory","lib/src/elements/instance_ref.dart"],["observatory","lib/src/elements/action_link.dart"],["observatory","lib/src/elements/nav_bar.dart"],["observatory","lib/src/elements/breakpoint_list.dart"],["observatory","lib/src/elements/class_ref.dart"],["observatory","lib/src/elements/class_tree.dart"],["observatory","lib/src/elements/eval_box.dart"],["observatory","lib/src/elements/eval_link.dart"],["observatory","lib/src/elements/field_ref.dart"],["observatory","lib/src/elements/function_ref.dart"],["observatory","lib/src/elements/library_ref.dart"],["observatory","lib/src/elements/script_inset.dart"],["observatory","lib/src/elements/script_ref.dart"],["observatory","lib/src/elements/class_view.dart"],["observatory","lib/src/elements/code_ref.dart"],["observatory","lib/src/elements/code_view.dart"],["observatory","lib/src/elements/error_view.dart"],["observatory","lib/src/elements/field_view.dart"],["observatory","lib/src/elements/stack_frame.dart"],["observatory","lib/src/elements/flag_list.dart"],["observatory","lib/src/elements/function_view.dart"],["observatory","lib/src/elements/heap_map.dart"],["observatory","lib/src/elements/io_view.dart"],["observatory","lib/src/elements/isolate_ref.dart"],["observatory","lib/src/elements/isolate_summary.dart"],["observatory","lib/src/elements/isolate_view.dart"],["observatory","lib/src/elements/inbound_reference.dart"],["observatory","lib/src/elements/instance_view.dart"],["observatory","lib/src/elements/json_view.dart"],["observatory","lib/src/elements/library_view.dart"],["observatory","lib/src/elements/metrics.dart"],["observatory","lib/src/elements/heap_profile.dart"],["observatory","lib/src/elements/sliding_checkbox.dart"],["observatory","lib/src/elements/isolate_profile.dart"],["observatory","lib/src/elements/script_view.dart"],["observatory","lib/src/elements/stack_trace.dart"],["observatory","lib/src/elements/vm_view.dart"],["observatory","lib/src/elements/service_view.dart"],["observatory","lib/src/elements/observatory_application.dart"],["observatory","lib/src/elements/service_exception_view.dart"],["observatory","lib/src/elements/service_error_view.dart"],["observatory","lib/src/elements/vm_connect.dart"],["observatory","lib/src/elements/vm_ref.dart"],["observatory","web/main.dart"]]}
+{"experimental_bootstrap":false,"script_ids":[["observatory","lib/src/elements/curly_block.dart"],["observatory","lib/src/elements/observatory_element.dart"],["observatory","lib/src/elements/service_ref.dart"],["observatory","lib/src/elements/instance_ref.dart"],["observatory","lib/src/elements/action_link.dart"],["observatory","lib/src/elements/nav_bar.dart"],["observatory","lib/src/elements/breakpoint_list.dart"],["observatory","lib/src/elements/class_ref.dart"],["observatory","lib/src/elements/class_tree.dart"],["observatory","lib/src/elements/error_ref.dart"],["observatory","lib/src/elements/eval_box.dart"],["observatory","lib/src/elements/eval_link.dart"],["observatory","lib/src/elements/field_ref.dart"],["observatory","lib/src/elements/function_ref.dart"],["observatory","lib/src/elements/library_ref.dart"],["observatory","lib/src/elements/script_inset.dart"],["observatory","lib/src/elements/script_ref.dart"],["observatory","lib/src/elements/class_view.dart"],["observatory","lib/src/elements/code_ref.dart"],["observatory","lib/src/elements/code_view.dart"],["observatory","lib/src/elements/error_view.dart"],["observatory","lib/src/elements/field_view.dart"],["observatory","lib/src/elements/stack_frame.dart"],["observatory","lib/src/elements/flag_list.dart"],["observatory","lib/src/elements/function_view.dart"],["observatory","lib/src/elements/heap_map.dart"],["observatory","lib/src/elements/io_view.dart"],["observatory","lib/src/elements/isolate_ref.dart"],["observatory","lib/src/elements/isolate_summary.dart"],["observatory","lib/src/elements/isolate_view.dart"],["observatory","lib/src/elements/inbound_reference.dart"],["observatory","lib/src/elements/instance_view.dart"],["observatory","lib/src/elements/json_view.dart"],["observatory","lib/src/elements/library_view.dart"],["observatory","lib/src/elements/metrics.dart"],["observatory","lib/src/elements/heap_profile.dart"],["observatory","lib/src/elements/sliding_checkbox.dart"],["observatory","lib/src/elements/isolate_profile.dart"],["observatory","lib/src/elements/script_view.dart"],["observatory","lib/src/elements/stack_trace.dart"],["observatory","lib/src/elements/vm_view.dart"],["observatory","lib/src/elements/service_view.dart"],["observatory","lib/src/elements/observatory_application.dart"],["observatory","lib/src/elements/service_exception_view.dart"],["observatory","lib/src/elements/service_error_view.dart"],["observatory","lib/src/elements/vm_connect.dart"],["observatory","lib/src/elements/vm_ref.dart"],["observatory","web/main.dart"]]}