Change the default sequences limit to 200 to speed up compress.

Has little or no impact on minification size in the majority of
cases but can speed up rollup builds significantly.

This sequences change also has the beneficial side effect of avoiding
"stack size exceeded" errors on very large input files.

The user is free to alter the sequences limit if they are so inclined.
The previous sequences limit was 2000. 20 is often sufficient.

lib/compress.js

@@ -80,7 +80,7 @@ function Compressor(options, false_by_default) {
         passes        : 1,
     }, true);
     var sequences = this.options["sequences"];
-    this.sequences_limit = sequences == 1 ? 2000 : sequences | 0;
+    this.sequences_limit = sequences == 1 ? 200 : sequences | 0;
     this.warnings_produced = {};
 };