JSDoc:Object<string, T> creates index signature

And `Object<number, T>` creates a numeric index signature. Other uses
still create `any` as before.

tests/baselines/reference/jsdocIndexSignature.symbols

@@ -0,0 +1,13 @@
+=== tests/cases/conformance/jsdoc/indices.js ===
+/** @type {Object.<string, number>} */
+var o1;
+>o1 : Symbol(o1, Decl(indices.js, 1, 3))
+
+/** @type {Object.<number, boolean>} */
+var o2;
+>o2 : Symbol(o2, Decl(indices.js, 3, 3))
+
+/** @type {Object.<boolean, string>} */
+var o3;
+>o3 : Symbol(o3, Decl(indices.js, 5, 3))
+

tests/baselines/reference/jsdocIndexSignature.types

@@ -0,0 +1,13 @@
+=== tests/cases/conformance/jsdoc/indices.js ===
+/** @type {Object.<string, number>} */
+var o1;
+>o1 : { [x: string]: number; }
+
+/** @type {Object.<number, boolean>} */
+var o2;
+>o2 : { [x: number]: boolean; }
+
+/** @type {Object.<boolean, string>} */
+var o3;
+>o3 : any
+

tests/cases/conformance/jsdoc/jsdocIndexSignature.ts

@@ -0,0 +1,10 @@
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+// @Filename: indices.js
+/** @type {Object.<string, number>} */
+var o1;
+/** @type {Object.<number, boolean>} */
+var o2;
+/** @type {Object.<boolean, string>} */
+var o3;