Test:Block-scoped definition of Promise works

Previously, a block-scoped definition of Promise like `class Promise<T>` in
a script would cause a crash

tests/baselines/reference/promiseDefinitionTest.js

@@ -0,0 +1,53 @@
+//// [promiseDefinitionTest.ts]
+class Promise<T> {}
+async function foo() {}
+const x = foo();
+
+
+//// [promiseDefinitionTest.js]
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
+    });
+};
+var __generator = (this && this.__generator) || function (thisArg, body) {
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
+    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    function verb(n) { return function (v) { return step([n, v]); }; }
+    function step(op) {
+        if (f) throw new TypeError("Generator is already executing.");
+        while (_) try {
+            if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t;
+            if (y = 0, t) op = [0, t.value];
+            switch (op[0]) {
+                case 0: case 1: t = op; break;
+                case 4: _.label++; return { value: op[1], done: false };
+                case 5: _.label++; y = op[1]; op = [0]; continue;
+                case 7: op = _.ops.pop(); _.trys.pop(); continue;
+                default:
+                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
+                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
+                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
+                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
+                    if (t[2]) _.ops.pop();
+                    _.trys.pop(); continue;
+            }
+            op = body.call(thisArg, _);
+        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
+        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
+    }
+};
+var Promise = (function () {
+    function Promise() {
+    }
+    return Promise;
+}());
+function foo() {
+    return __awaiter(this, void 0, void 0, function () { return __generator(this, function (_a) {
+        return [2 /*return*/];
+    }); });
+}
+var x = foo();

tests/baselines/reference/promiseDefinitionTest.symbols

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+=== tests/cases/compiler/promiseDefinitionTest.ts ===
+class Promise<T> {}
+>Promise : Symbol(Promise, Decl(lib.d.ts, --, --), Decl(promiseDefinitionTest.ts, 0, 0))
+>T : Symbol(T, Decl(lib.d.ts, --, --), Decl(promiseDefinitionTest.ts, 0, 14))
+
+async function foo() {}
+>foo : Symbol(foo, Decl(promiseDefinitionTest.ts, 0, 19))
+
+const x = foo();
+>x : Symbol(x, Decl(promiseDefinitionTest.ts, 2, 5))
+>foo : Symbol(foo, Decl(promiseDefinitionTest.ts, 0, 19))
+

tests/baselines/reference/promiseDefinitionTest.types

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/promiseDefinitionTest.ts ===
+class Promise<T> {}
+>Promise : Promise<T>
+>T : T
+
+async function foo() {}
+>foo : () => Promise<void>
+
+const x = foo();
+>x : Promise<void>
+>foo() : Promise<void>
+>foo : () => Promise<void>
+

tests/cases/compiler/promiseDefinitionTest.ts

@@ -0,0 +1,4 @@
+// @target: es5
+class Promise<T> {}
+async function foo() {}
+const x = foo();