Add passes compress option. Fix duplicate compress warnings.

test/mocha/minify.js

@@ -0,0 +1,11 @@
+var Uglify = require('../../');
+var assert = require("assert");
+
+describe("minify", function() {
+    it("Should test basic sanity of minify with default options", function() {
+        var js = 'function foo(bar) { if (bar) return 3; else return 7; var u = not_called(); }';
+        var result = Uglify.minify(js, {fromString: true});
+        assert.strictEqual(result.code, 'function foo(n){return n?3:7}');
+    });
+});
+