extract no extension but non ts extensions allowed into its own clause. make boolean expression more natural to read

Author: jrieken

src/compiler/parser.ts

@@ -5231,7 +5231,10 @@ module ts {
                 }
             }
             else {
-                if (!((options.allowNonTsExtensions && findSourceFile(filename, isDefaultLib, refFile, refPos, refEnd)) || findSourceFile(filename + ".ts", isDefaultLib, refFile, refPos, refEnd) || findSourceFile(filename + ".d.ts", isDefaultLib, refFile, refPos, refEnd))) {
+                if(options.allowNonTsExtensions && !findSourceFile(filename, isDefaultLib, refFile, refPos, refEnd)) {
+                    diagnostic = Diagnostics.File_0_not_found;
+                }
+                else if (!findSourceFile(filename + ".ts", isDefaultLib, refFile, refPos, refEnd) && !findSourceFile(filename + ".d.ts", isDefaultLib, refFile, refPos, refEnd)) {
                     diagnostic = Diagnostics.File_0_not_found;
                     filename += ".ts";
                 }