added .d.ts generation tests

tests/baselines/reference/constEnumDeclarations.js

@@ -0,0 +1,28 @@
+//// [constEnumDeclarations.ts]
+
+const enum E {
+    A = 1,
+    B = 2,
+    C = A | B
+}
+
+const enum E2 {
+    A = 1,
+    B,
+    C
+}
+
+//// [constEnumDeclarations.js]
+
+
+//// [constEnumDeclarations.d.ts]
+declare const enum E {
+    A = 1,
+    B = 2,
+    C = 3,
+}
+declare const enum E2 {
+    A = 1,
+    B = 2,
+    C = 3,
+}

tests/baselines/reference/constEnumDeclarations.types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/constEnumDeclarations.ts ===
+
+const enum E {
+>E : E
+
+    A = 1,
+>A : E
+
+    B = 2,
+>B : E
+
+    C = A | B
+>C : E
+>A | B : number
+>A : E
+>B : E
+}
+
+const enum E2 {
+>E2 : E2
+
+    A = 1,
+>A : E2
+
+    B,
+>B : E2
+
+    C
+>C : E2
+}

tests/cases/compiler/constEnumDeclarations.ts

@@ -0,0 +1,13 @@
+// @declaration: true
+
+const enum E {
+    A = 1,
+    B = 2,
+    C = A | B
+}
+
+const enum E2 {
+    A = 1,
+    B,
+    C
+}