Function isTypePresencePossible

test/fixtures/snapshot/typescript.js:70855–70861

(type, propName, assumeTrue)

                return type;
            }
            function isTypePresencePossible(type, propName, assumeTrue) {
                var prop = getPropertyOfType(type, propName);
                if (prop) {
                    return prop.flags & 16777216 /* SymbolFlags.Optional */ ? true : assumeTrue;
                }
                return getApplicableIndexInfoForName(type, propName) ? true : !assumeTrue;
            }
            function narrowByInKeyword(type, name, assumeTrue) {
                if (type.flags & 1048576 /* TypeFlags.Union */
                    || type.flags & 524288 /* TypeFlags.Object */ && declaredType !== type