Add optional message to assert in Dart2js.

pkg/compiler/lib/src/resolution/members.dart

Index: pkg/compiler/lib/src/resolution/members.dart
diff --git a/pkg/compiler/lib/src/resolution/members.dart b/pkg/compiler/lib/src/resolution/members.dart
index 46294f78446e0db19c911165f7576719ff74180d..4f7777d0ff0f391cff9fb4e5d9be12f78a5b6762 100644
--- a/pkg/compiler/lib/src/resolution/members.dart
+++ b/pkg/compiler/lib/src/resolution/members.dart
@@ -499,6 +499,13 @@ class ResolverVisitor extends MappingVisitor<ResolutionResult> {
     }
   }
 
+  ResolutionResult visitAssert(Assert node) {
+    registry.registerAssert(node.hasMessage);
+    visit(node.condition);
+    visit(node.message);
+    return const NoneResult();
+  }
+
   ResolutionResult visitCascade(Cascade node) {
     visit(node.expression);
     return const NoneResult();
@@ -1526,34 +1533,6 @@ class ResolverVisitor extends MappingVisitor<ResolutionResult> {
     return const NoneResult();
   }
 
-  /// Handle a, possibly invalid, assertion, like `assert(cond)` or `assert()`.
-  ResolutionResult handleAssert(Send node) {
-    assert(invariant(node, node.isCall,
-        message: "Unexpected assert: $node"));
-    // If this send is of the form "assert(expr);", then
-    // this is an assertion.
-
-    CallStructure callStructure =
-        resolveArguments(node.argumentsNode).callStructure;
-    SendStructure sendStructure = const AssertStructure();
-    if (callStructure.argumentCount != 1) {
-      compiler.reportError(
-          node.selector,
-          MessageKind.WRONG_NUMBER_OF_ARGUMENTS_FOR_ASSERT,
-          {'argumentCount': callStructure.argumentCount});
-      sendStructure = const InvalidAssertStructure();
-    } else if (callStructure.namedArgumentCount != 0) {
-      compiler.reportError(
-          node.selector,
-          MessageKind.ASSERT_IS_GIVEN_NAMED_ARGUMENTS,
-          {'argumentCount': callStructure.namedArgumentCount});
-      sendStructure = const InvalidAssertStructure();
-    }
-    registry.registerAssert(node);
-    registry.registerSendStructure(node, sendStructure);
-    return const AssertResult();
-  }
-
   /// Handle access of a property of [name] on `this`, like `this.name` and
   /// `this.name()`, or `name` and `name()` in instance context.
   ResolutionResult handleThisPropertyAccess(Send node, Name name) {
@@ -3027,10 +3006,7 @@ class ResolverVisitor extends MappingVisitor<ResolutionResult> {
       return handleExpressionInvoke(node);
     }
     String text = selector.source;
-    if (text == 'assert') {
-      // `assert()`.
-      return handleAssert(node);
-    } else if (text == 'this') {
+    if (text == 'this') {
       // `this()`.
       return handleThisAccess(node);
     }