No, and they shouldn't be. Modern web browsers are "streamlined", which is what they ought to be and how they best serve their users - by being a minimal window to access the real protagonist, web content.

"Innovative" ideas should be tested in the form of separate applications or plugins, not shoehorned into the core tool that people use for almost all their access to Internet; experimenting with innovative ideas in this minimal tool is likely to break some workflows for most people.