Split shim into browser support related files

Half of the source-code is related to shims that ensure PST work on every browser, we need to decouple the final code from this shim, and use "require" syntax to include the pieces inside the source code.

Since the shims can't be tested for code coverage, they must be ignored in the same.

In this processes we need to add a build flag to determine witch shims should be build with the final lib.
