Brandon Eich was hired to integrate the Scheme programming langauge into the Netscape browser. But when Netscape cut a deal with Sun Microsystems to bring Java Applets to their browser, his mission was altered to create a more Java-like langauge. He developed a prototype in only ten days, that blended Java syntax, the Self object-orientation approach, and Scheme functionality.
The ECMA standard is maintained by ECMA International, not the W3C. However, its development process is very similar, involving stakeholders developing proposals for new and improved features.