Google Chrome and Firefox does allows to search Google for highlighted keywords from context menu in their browsers, Highlight to Search extension from Google for Chrome allows to search your keywords by highlighting instead of typing them into search box.

Highlight to Search Google Chrome extension

After installing Highlight to Search extension you just need to select or highlight particular keyword,a magnifying glass icon appears below the highlighted keyword .Click that icon or the keywords,search-box with autocomplete enabled appears for user to search quickly and easily.

Install Highlight to Search extension [via]