[vm/wasm] Fix patches

Remove invalid @patch annotations and add explicit bound to Expando patches

This is in preparation for a change in how the CFE handles patches as parts instead of libraries.

TEST=ci

Change-Id: Ie3f3e5053870ce4f131404200c64b536e647a7ca
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/413220
Reviewed-by: Alexander Markov <[email protected]>
Commit-Queue: Johnni Winther <[email protected]>

Author: johnniwinther

sdk/lib/_internal/vm/lib/concurrent_patch.dart

@@ -22,7 +22,6 @@ base class _MutexImpl extends NativeFieldWrapperClass1 implements Mutex {
   @Native<Void Function(Handle)>(symbol: "Mutex_Initialize")
   external void _initialize();
 
-  @patch
   @Native<Handle Function(Handle, Handle)>(symbol: "Mutex_RunLocked")
   external Object _runLocked(Object action);
 
@@ -48,15 +47,12 @@ base class _ConditionVariableImpl extends NativeFieldWrapperClass1
   @Native<Void Function(Handle)>(symbol: "ConditionVariable_Initialize")
   external void _initialize();
 
-  @patch
   @Native<Void Function(Handle, Handle)>(symbol: "ConditionVariable_Wait")
   external void wait(Mutex mutex);
 
-  @patch
   @Native<Void Function(Handle)>(symbol: "ConditionVariable_Notify")
   external void notify();
 
-  @patch
   @Native<Void Function(Handle)>(symbol: "ConditionVariable_NotifyAll")
   external void notifyAll();
 }

sdk/lib/_internal/vm/lib/expando_patch.dart

@@ -16,7 +16,7 @@ void _rehashObjects(List objects) {
 
 @patch
 @pragma("vm:entry-point")
-class Expando<T> {
+class Expando<T extends Object> {
   @patch
   Expando([String? name])
     : name = name,

sdk/lib/_internal/wasm/lib/weak_patch.dart

@@ -26,7 +26,7 @@ void _checkValidWeakTarget(Object object) {
 }
 
 @patch
-class Expando<T> {
+class Expando<T extends Object> {
   WasmExternRef? _jsWeakMap;
 
   @patch