Bug 1344629 - Part 6: Rewrite unnecessary uses of nsLiteralString. r=dbaron

There's an antipattern where nsLiteralString is used as an unnecessary intermediary in converting from CharT* to CharT*,
e.g. CallAFunctionThatTakesACharPointer(NS_LITERAL_CSTRING("foo").get());
or
NS_NAMED_LITERAL_STRING(foo, "abc");
CallAFunctionThatTakesACharPointer(foo.get());

This patch rewrites the callsites that can be trivially changed to use char*/char16_t*.

I'd somewhat like to remove nsTLiteralString::get() altogether, but in code that's less straightforward than these examples, get() is useful enough to keep.

MozReview-Commit-ID: Kh1rUziVllo

widget/windows/nsFilePicker.cpp

@@ -499,13 +499,11 @@ nsFilePicker::ShowFilePicker(const nsString& aInitialDir)
     dialog->SetFileName(mDefaultFilename.get());
   }
   
-  NS_NAMED_LITERAL_STRING(htmExt, "html");
-
   // default extension to append to new files
   if (!mDefaultExtension.IsEmpty()) {
     dialog->SetDefaultExtension(mDefaultExtension.get());
   } else if (IsDefaultPathHtml()) {
-    dialog->SetDefaultExtension(htmExt.get());
+    dialog->SetDefaultExtension(L"html");
   }
 
   // initial location