add completion in type argument list

pkg/analysis_server/lib/src/services/completion/optype.dart

Index: pkg/analysis_server/lib/src/services/completion/optype.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/optype.dart b/pkg/analysis_server/lib/src/services/completion/optype.dart
index cba56957243a1931b1da0629605c3b439c36503d..5bb865d18556b6e15a5a1fc7936b3aea9d7606cc 100644
--- a/pkg/analysis_server/lib/src/services/completion/optype.dart
+++ b/pkg/analysis_server/lib/src/services/completion/optype.dart
@@ -139,6 +139,22 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
   @override
   void visitBinaryExpression(BinaryExpression node) {
     if (identical(entity, node.rightOperand)) {
+      // An empty type argument list is parsed as a binary expression
+      // `C<>` is parsed as `C < `
+      Object entity = this.entity;
+      if (entity is SimpleIdentifier && entity.isSynthetic) {
+        Token operator = node.operator;
+        if (operator != null && operator.lexeme == '<') {
+          Token next = entity.token.next;
+          if (next is StringToken && next.lexeme.length == 0) {
+            next = next.next;
+          }
+          if (next != null && next.lexeme == '>') {
+            optype.includeTypeNameSuggestions = true;
+            return;
+          }
+        }
+      }
       optype.includeReturnValueSuggestions = true;
       optype.includeTypeNameSuggestions = true;
     }
@@ -496,6 +512,17 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
   }
 
   @override
+  visitTypeArgumentList(TypeArgumentList node) {
+    NodeList<TypeName> arguments = node.arguments;
+    for (TypeName typeName in arguments) {
+      if (identical(entity, typeName)) {
+        optype.includeTypeNameSuggestions = true;
+        break;
+      }
+    }
+  }
+
+  @override
   void visitTypeName(TypeName node) {
     // The entity won't be the first child entity (node.name), since
     // CompletionTarget would have chosen an edge higher in the parse tree.  So