Constant folding in computed enum members

why not write this as:
```TypeScript
if (isConstEnumDeclaration(<EnumDeclaration>node)) {
        bindDeclaration(<Declaration>node, SymbolFlags.Enum | SymbolFlags.ConstEnum, SymbolFlags.ConstEnumExcludes, /*isBlockScopeContainer*/ false);
}
else {
        bindDeclaration(<Declaration>node, SymbolFlags.Enum, SymbolFlags.EnumExcludes, /*isBlockScopeContainer*/ false);
}
break;
```