Don't error when 'reserved' names appear in ambient contexts.

Fixes microsoft#8293

Author: RyanCavanaugh

src/compiler/binder.ts

@@ -1377,7 +1377,8 @@ namespace ts {
             if (inStrictMode &&
                 node.originalKeywordKind >= SyntaxKind.FirstFutureReservedWord &&
                 node.originalKeywordKind <= SyntaxKind.LastFutureReservedWord &&
-                !isIdentifierName(node)) {
+                !isIdentifierName(node) &&
+                !isInAmbientContext(node)) {
 
                 // Report error only if there are no parse errors in file
                 if (!file.parseDiagnostics.length) {

tests/baselines/reference/ambientNameRestrictions.errors.txt

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/ambientNameRestrictions.ts ===
+export declare namespace Foo {
+>Foo : Symbol(Foo, Decl(ambientNameRestrictions.ts, 0, 0))
+
+  export var static: any;
+>static : Symbol(static, Decl(ambientNameRestrictions.ts, 1, 12))
+}
+

tests/baselines/reference/ambientNameRestrictions.symbols

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/ambientNameRestrictions.ts ===
+export declare namespace Foo {
+>Foo : typeof Foo
+
+  export var static: any;
+>static : any
+}
+