[ddc] Bump default language version to 2.15.0

Start using constructor tearoffs in libraries that have been migrated to
null safety.

Change-Id: I1a448a42b811c2f278d25a823356ee60a452848f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/223341
Reviewed-by: Anna Gringauze <annagrin@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>

.dart_tool/package_config.json

@@ -262,7 +262,7 @@
       "name": "dev_compiler",
       "rootUri": "../pkg/dev_compiler",
       "packageUri": "lib/",
-      "languageVersion": "2.12"
+      "languageVersion": "2.15"
     },
     {
       "name": "devtools_server",
@@ -817,4 +817,4 @@
       "languageVersion": "2.12"
     }
   ]
-}
+}

pkg/dev_compiler/lib/src/kernel/module_symbols.dart

@@ -142,20 +142,17 @@ class ModuleSymbols implements SymbolTableElement {
   ModuleSymbols.fromJson(Map<String, dynamic> json)
       : version = _readAndValidateVersionFromJson(json['version']),
         moduleName = _createValue(json['moduleName']),
-        libraries = _createObjectList(
-            json['libraries'], (json) => LibrarySymbol.fromJson(json)),
-        scripts =
-            _createObjectList(json['scripts'], (json) => Script.fromJson(json)),
-        classes = _createObjectList(
-            json['classes'], (json) => ClassSymbol.fromJson(json)),
+        libraries =
+            _createObjectList(json['libraries'], LibrarySymbol.fromJson),
+        scripts = _createObjectList(json['scripts'], Script.fromJson),
+        classes = _createObjectList(json['classes'], ClassSymbol.fromJson),
         functionTypes = _createObjectList(
-            json['functionTypes'], (json) => FunctionTypeSymbol.fromJson(json)),
-        functions = _createObjectList(
-            json['functions'], (json) => FunctionSymbol.fromJson(json)),
-        scopes = _createObjectList(
-            json['scopes'], (json) => ScopeSymbol.fromJson(json)),
-        variables = _createObjectList(
-            json['variables'], (json) => VariableSymbol.fromJson(json));
+            json['functionTypes'], FunctionTypeSymbol.fromJson),
+        functions =
+            _createObjectList(json['functions'], FunctionSymbol.fromJson),
+        scopes = _createObjectList(json['scopes'], ScopeSymbol.fromJson),
+        variables =
+            _createObjectList(json['variables'], VariableSymbol.fromJson);
 
   @override
   Map<String, dynamic> toJson() {
@@ -208,8 +205,8 @@ class Symbol implements SymbolTableElement {
   Symbol.fromJson(Map<String, dynamic> json)
       : localId = _createValue(json['localId']),
         scopeId = _createValue(json['scopeId']),
-        location = _createNullableObject(
-            json['location'], (json) => SourceLocation.fromJson(json));
+        location =
+            _createNullableObject(json['location'], SourceLocation.fromJson);
 
   @override
   Map<String, dynamic> toJson() {
@@ -527,8 +524,8 @@ class LibrarySymbol extends ScopeSymbol {
       : name = _createValue(json['name'], ifNull: ''),
         uri = _createValue(json['uri']),
         scriptIds = _createValueList(json['scriptIds']),
-        dependencies = _createObjectList(json['dependencies'],
-            (json) => LibrarySymbolDependency.fromJson(json)),
+        dependencies = _createObjectList(
+            json['dependencies'], LibrarySymbolDependency.fromJson),
         super.fromJson(json);
 
   @override

pkg/dev_compiler/pubspec.yaml

@@ -3,7 +3,7 @@ name: dev_compiler
 publish_to: none
 
 environment:
-  sdk: '>=2.12.0 <3.0.0'
+  sdk: '>=2.15.0 <3.0.0'
 
 dependencies:
   _fe_analyzer_shared: any