clang-format: [JS] fix non-null assertion operator recognition.

[mprobst]

Summary

getIdentifierInfo() includes all keywords, whereas non-null assertion
operators should only be recognized after non-keywords or pseudo keywords.
Ideally this should list all tokens that clang-format recognizes as a keyword,
but that are pseudo or no keywords in JS. For the time being, just recognize
the specific bits users ran into (namespace in this case).

[djasper]

A test case might be useful.

cfe/trunk/lib/Format/TokenAnnotator.cpp

private:
   void determineTokenType(FormatToken &Current) {
     if (!Current.is(TT_Unknown))
       // The token type is already known.
       return;
 
     if (Style.Language == FormatStyle::LK_JavaScript) {
       if (Current.is(tok::exclaim)) {
         if (Current.Previous &&
-            (Current.Previous->Tok.getIdentifierInfo() ||
-             Current.Previous->isOneOf(tok::identifier, tok::r_paren,
-                                       tok::r_square, tok::r_brace) ||
+            (Current.Previous->isOneOf(tok::identifier, tok::kw_namespace,
+                                       tok::r_paren, tok::r_square,
+                                       tok::r_brace) ||
              Current.Previous->Tok.isLiteral())) {
           Current.Type = TT_JsNonNullAssertion;
           return;
         }
         if (Current.Next &&
             Current.Next->isOneOf(TT_BinaryOperator, Keywords.kw_as)) {
           Current.Type = TT_JsNonNullAssertion;
           return;

cfe/trunk/unittests/Format/FormatTestJS.cpp

TEST_F(FormatTestJS, NonNullAssertionOperator) {
   verifyFormat("let x = {foo: 1}!;\n");
   verifyFormat(
       "let x = hello.foo()!\n"
       "            .foo()!\n"
       "            .foo()!\n"
       "            .foo()!;\n",
       getGoogleJSStyleWithColumns(20));
   verifyFormat("let x = namespace!;\n");
+  verifyFormat("return !!x;\n");
 }
 
 TEST_F(FormatTestJS, Conditional) {
   verifyFormat("y = x ? 1 : 2;");
   verifyFormat("x ? 1 : 2;");
   verifyFormat("class Foo {\n"
                "  field = true ? 1 : 2;\n"
                "  method(a = true ? 1 : 2) {}\n"