[clang-format] Simplify TT_SelectorName assignment logic

[krasimir]

Summary

While trying to understand TT_SelectorName, I found 2 redundant checks.
Removing them doesn't cause any tests to fail.

[djasper]

For the test introduced in https://reviews.llvm.org/rL262291, either of the changes causes a TT_SelectorName to become a TT_Unknown. So lets figure out how to make this a difference in observable formatting behavior instead of removing these checks.

lib/Format/TokenAnnotator.cpp

if (CurrentToken) {
           return true;
         }
         if (CurrentToken->isOneOf(tok::r_paren, tok::r_square))
           return false;
         updateParameterCount(Left, CurrentToken);
         if (CurrentToken->isOneOf(tok::colon, tok::l_brace)) {
           FormatToken *Previous = CurrentToken->getPreviousNonComment();
           if (((CurrentToken->is(tok::colon) &&
-                (!Contexts.back().ColonIsDictLiteral || !Style.isCpp())) ||
+                !Contexts.back().ColonIsDictLiteral) ||
                Style.Language == FormatStyle::LK_Proto) &&
-              (Previous->Tok.getIdentifierInfo() ||
-               Previous->is(tok::string_literal)))
+              Previous->Tok.getIdentifierInfo())
             Previous->Type = TT_SelectorName;
           if (CurrentToken->is(tok::colon) ||
               Style.Language == FormatStyle::LK_JavaScript)
             Left->Type = TT_DictLiteral;
         }
         if (CurrentToken->is(tok::comma) &&
             Style.Language == FormatStyle::LK_JavaScript)
           Left->Type = TT_DictLiteral;