Revert "Emit declarations for typedefs that are needed by reflection."

sdk/lib/_internal/compiler/implementation/runtime_data.dart

-/// Contains encoding, decoding and detection functionality for the
-/// representation of program data at runtime.
-///
-/// This library is shared between the compiler and the runtime system.
-library dart2js.runtime_data;
-
-
-String encodeTypedefFieldDescriptor(int typeIndex) {
-  return ":$typeIndex;";
-}
-
-bool isTypedefDescriptor(String descriptor) {
-  return descriptor.startsWith(':');
-}
-
-int getTypeFromTypedef(String descriptor) {
-  return int.parse(descriptor.substring(1, descriptor.length - 1));
-}