Handle symbol literals

(Hitting this in angular / stack_trace.)

[email protected]

Review URL: https://codereview.chromium.org/1060813008

Author: vsmenon

pkg/dev_compiler/lib/runtime/dart/_js_helper.js

@@ -2040,7 +2040,7 @@ var _js_helper;
         });
       }
       let selectorName = `${_foreign_helper.JS_GET_NAME("CALL_PREFIX")}$${argumentCount}${names}`;
-      return dart.dsend(func, 'noSuchMethod', createUnmangledInvocationMirror(dart.throw_("Unimplemented SymbolLiteral: #call"), selectorName, JSInvocationMirror.METHOD, arguments$, namedArgumentList));
+      return dart.dsend(func, 'noSuchMethod', createUnmangledInvocationMirror(/* Unimplemented const */new _internal.Symbol("call"), selectorName, JSInvocationMirror.METHOD, arguments$, namedArgumentList));
     }
     static applyFunction(func, positionalArguments, namedArguments) {
       return namedArguments == null ? Primitives.applyFunctionWithPositionalArguments(func, positionalArguments) : Primitives.applyFunctionWithNamedArguments(func, positionalArguments, namedArguments);

pkg/dev_compiler/lib/src/codegen/js_codegen.dart

@@ -2052,6 +2052,16 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   @override
   visitNullLiteral(NullLiteral node) => new JS.LiteralNull();
 
+  @override
+  visitSymbolLiteral(SymbolLiteral node) {
+    // TODO(vsm): When we canonicalize, we need to treat private symbols
+    // correctly.
+    // TODO(vsm): Make this core.Symbol instead.
+    var name = js.escapedString(node.components.join('.'));
+    var symbol = js.call('new _internal.Symbol(#)', name);
+    return js.commentExpression('Unimplemented const', symbol);
+  }
+
   @override
   visitListLiteral(ListLiteral node) {
     JS.Expression list = new JS.ArrayInitializer(_visitList(node.elements));