Add pre-built version of JS libraries

Author: romaninsh

js/.gitignore

@@ -8,7 +8,6 @@ pids
 *.seed
 
 # Directory for instrumented libs generated by jscoverage/JSCover
-lib-cov
 
 # Coverage directory used by tools like istanbul
 coverage
@@ -30,4 +29,3 @@ node_modules
 .idea
 .vscode
 
-lib