Migrate package:dart_internal to null safety.

This also highlighted a couple of mistakes in the patch files for

dart:_internal and the test.
Change-Id: I60b4e7d5673d64f85a95108c9e03f9328249b9d0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153021
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Jake Macdonald <jakemac@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>

.dart_tool/package_config.json

@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2020-08-13T10:20:32.864803",
+  "generated": "2020-08-17T14:05:33.104579",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
@@ -202,7 +202,7 @@
       "name": "dart_internal",
       "rootUri": "../pkg/dart_internal",
       "packageUri": "lib/",
-      "languageVersion": "2.0"
+      "languageVersion": "2.10"
     },
     {
       "name": "dart_style",

pkg/dart_internal/lib/extract_type_arguments.dart

@@ -22,8 +22,8 @@ import 'dart:_internal' as internal;
 /// print(extractIterableTypeArgument(iterable, <T>() => new Set<T>());
 /// // Prints "Instance of 'Set<int>'".
 /// ```
-Object extractIterableTypeArgument(
-        Iterable iterable, Object Function<T>() extract) =>
+Object? extractIterableTypeArgument(
+        Iterable iterable, Object? Function<T>() extract) =>
     internal.extractTypeArguments<Iterable>(iterable, extract);
 
 /// Given a [Map], invokes [extract], passing the [map]'s key and value type
@@ -40,5 +40,5 @@ Object extractIterableTypeArgument(
 ///   // Prints "Instance of 'Two<String, int>'".
 /// }
 /// ```
-Object extractMapTypeArguments(Map map, Object Function<K, V>() extract) =>
+Object? extractMapTypeArguments(Map map, Object? Function<K, V>() extract) =>
     internal.extractTypeArguments<Map>(map, extract);

pkg/dart_internal/pubspec.yaml

@@ -1,5 +1,7 @@
 name: dart_internal
-version: 0.1.10
+version: 0.1.11-nullsafety
+author: "Dart Team <misc@dartlang.org>"
+homepage: http://www.dartlang.org
 repository: https://github.com/dart-lang/sdk/tree/master/pkg/dart_internal
 description: >
   This package is not intended for wide use. It provides a temporary API to
@@ -16,4 +18,4 @@ description: >
 environment:
   # Restrict the upper bound so that we can remove support for this in a later
   # version of the SDK without it being a breaking change.
-  sdk: ">=2.0.0 <2.10.0"
+  sdk: ">=2.10.0-0.0 <2.10.0"

sdk/lib/_internal/js_runtime/lib/internal_patch.dart

@@ -57,7 +57,7 @@ List<T> makeFixedListUnmodifiable<T>(List<T> fixedLengthList) {
 
 @patch
 @pragma('dart2js:noInline')
-Object extractTypeArguments<T>(T instance, Function extract) {
+Object? extractTypeArguments<T>(T instance, Function extract) {
   // This function is recognized and replaced with calls to js_runtime.
 
   // This call to [extract] is required to model that the function is called and

sdk/lib/_internal/vm/lib/internal_patch.dart

@@ -32,7 +32,7 @@ List<T> makeFixedListUnmodifiable<T>(List<T> fixedLengthList)
     native "Internal_makeFixedListUnmodifiable";
 
 @patch
-Object extractTypeArguments<T>(T instance, Function extract)
+Object? extractTypeArguments<T>(T instance, Function extract)
     native "Internal_extractTypeArguments";
 
 /// The returned string is a [_OneByteString] with uninitialized content.

tests/language/unsorted/extract_type_arguments_test.dart

@@ -39,7 +39,7 @@ testExtractIterableTypeArgument() {
   Expect.isTrue(called);
 
   // Returns result of function.
-  Object result = extractIterableTypeArgument(object, <T>() => new Set<T>());
+  Object? result = extractIterableTypeArgument(object, <T>() => new Set<T>());
   Expect.isTrue(result is Set<int>);
   Expect.isFalse(result is Set<bool>);
 
@@ -63,7 +63,7 @@ testExtractMapTypeArguments() {
   Expect.isTrue(called);
 
   // Returns result of function.
-  Object result = extractMapTypeArguments(object, <K, V>() => new Two<K, V>());
+  Object? result = extractMapTypeArguments(object, <K, V>() => new Two<K, V>());
   Expect.isTrue(result is Two<String, int>);
   Expect.isFalse(result is Two<int, String>);