tighten checks for 'qx.bom.client.EcmaScript'
[BUG #8468] add support for compressing esprima trees (Mozilla Parser AST format)
[BUG #8468] add support for optimizing qx.core.Environment.get()|select() calls
[BUG #8468] activate optimization for qx.core.Environment.get()|select() calls
[BUG #8468] use variants optimization during build