Use correct base primitive type

Author: rbuckton

src/compiler/checker.ts

@@ -18842,7 +18842,7 @@ namespace ts {
                     // If the type parameter is constrained to the base primitive type we're checking for,
                     // consider this a literal context. For example, given a type parameter 'T extends string',
                     // this causes us to infer string literal types for T.
-                    if (constraint.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.Boolean | TypeFlags.Enum | TypeFlags.Symbol)) {
+                    if (constraint.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.Boolean | TypeFlags.Enum | TypeFlags.ESSymbol)) {
                         return true;
                     }
                     contextualType = constraint;