fix(Compiler): Add a workaround for #908, "extra" type inference for tokens.

After this CL, we will infer, in the view compiler:
  `Provider<dynamic>(OpaqueToken<T>)`
as
  `Provider<T>(OpaqueToken<T>)`

This isn't strictly right, but its better than emitting incorrect types
(dynamic), which can block Dart2. Once #908 is fixed, we can revert this
change.

PiperOrigin-RevId: 186788142

Author: matanlurey

angular/lib/src/source_gen/template_compiler/compile_metadata.dart

@@ -117,6 +117,19 @@ class CompileTypeMetadataVisitor
       }
     }
     final token = dart_objects.getField(provider, 'token');
+
+    // Workaround for analyzer bug.
+    // https://github.com/dart-lang/angular/issues/917
+    if (multiType == null &&
+        $OpaqueToken.isAssignableFromType(token.type) &&
+        token.type.typeArguments.isNotEmpty) {
+      // If we see a Provider<dynamic> (no generic type), but the token is a
+      // typed OpaqueToken<T>, pretend that the Provider was actually inferred
+      // as Provider<T>.
+      final opaqueTokenGenericType = token.type.typeArguments.first.element;
+      multiType = _getCompileTypeMetadata(opaqueTokenGenericType);
+    }
+
     return new CompileProviderMetadata(
       token: _token(token),
       useClass: _getUseClass(provider, token),