Parse an object literal property as shorthand unless followed by '(' or ':' (#28121)

tests/cases/conformance/parser/ecmascript5/RegressionTests/parser512097.ts

@@ -1,4 +1,4 @@
-var tt = { aa; } // After this point, no useful parsing occurs in the entire file
+var tt = { aa; }
 
 if (true) {
 }

tests/cases/fourslash/completionsAtIncompleteObjectLiteralProperty.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+// @noLib: true
+
+////f({
+////    a/**/
+////    xyz: ``,
+////});
+////declare function f(options: { abc?: number, xyz?: string }): void;
+
+verify.completions({
+    marker: "",
+    exact: ["abc"],
+});