Disable two lint rules which are being removed. (#8488)

Each of these are going to be removed soon.

* avoid_null_checks_in_equality_operators
* unsafe_html

Work towards https://github.com/dart-lang/linter/issues/5063 and https://github.com/dart-lang/linter/issues/5001

Author: srawlins

packages/analysis_options.yaml

@@ -43,7 +43,6 @@ linter:
     - avoid_function_literals_in_foreach_calls
     - avoid_init_to_null
     # - avoid_js_rounded_ints # only useful when targeting JS runtime
-    - avoid_null_checks_in_equality_operators
     # - avoid_positional_boolean_parameters # not yet tested
     - avoid_print
     # - avoid_private_typedef_functions # we prefer having typedef (discussion in https://github.com/flutter/flutter/pull/16356)
@@ -138,7 +137,6 @@ linter:
     - unnecessary_statements
     - unnecessary_this
     - unrelated_type_equality_checks
-    - unsafe_html
     - use_rethrow_when_possible
     # - use_setters_to_change_properties # not yet tested
     # - use_string_buffers # https://github.com/dart-lang/linter/pull/664

packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart

@@ -87,7 +87,6 @@ class EmbeddedExtensionControllerImpl extends EmbeddedExtensionController
     _extensionIFrame = HTMLIFrameElement()
       // This url is safe because we built it ourselves and it does not include
       // any user input.
-      // ignore: unsafe_html
       ..src = extensionUrl
       ..allow = 'usb';
     _extensionIFrame.style

packages/devtools_app/lib/src/screens/performance/panes/timeline_events/perfetto/_perfetto_controller_web.dart

@@ -167,7 +167,6 @@ class PerfettoControllerImpl extends PerfettoController {
     _perfettoIFrame = HTMLIFrameElement()
       // This url is safe because we built it ourselves and it does not include
       // any user input.
-      // ignore: unsafe_html
       ..src = perfettoUrl
       ..allow = 'usb';
     _perfettoIFrame.style