addDefaultReactImport(specifier) {
    const info = ReactImports.get(this);
    ReactImports.set(this, Object.assign({}, info, {
      defaultReactImports: (info.defaultReactImports || []).concat(specifier),
    }));
  }
Add the default React import specifier to the scope

@param {ASTNode} specifier The AST Node of the default React import
@returns {void}