drop unused "class" definition IIFEs (#2923)

fixes #805

test/compress/collapse_vars.js

@@ -4619,3 +4619,26 @@ issue_2914_2: {
     }
     expect_stdout: "0"
 }
+
+issue_805: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+    }
+    input: {
+        function f() {
+            function Foo(){}
+            Foo.prototype = {};
+            Foo.prototype.bar = 42;
+            return Foo;
+        }
+    }
+    expect: {
+        function f() {
+            function Foo(){}
+            (Foo.prototype = {}).bar = 42;
+            return Foo;
+        }
+    }
+}

test/compress/drop-unused.js

@@ -1719,3 +1719,69 @@ issue_2846: {
     }
     expect_stdout: "0"
 }
+
+issue_805_1: {
+    options = {
+        inline: true,
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            var unused = function() {};
+            unused.prototype[a()] = 42;
+            (unused.prototype.bar = function() {
+                console.log("bar");
+            })();
+            return unused;
+        })(function() {
+            console.log("foo");
+            return "foo";
+        });
+    }
+    expect: {
+        console.log("foo"),
+        console.log("bar");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}
+
+issue_805_2: {
+    options = {
+        inline: true,
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            function unused() {}
+            unused.prototype[a()] = 42;
+            (unused.prototype.bar = function() {
+                console.log("bar");
+            })();
+            return unused;
+        })(function() {
+            console.log("foo");
+            return "foo";
+        });
+    }
+    expect: {
+        console.log("foo"),
+        console.log("bar");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}

test/mocha/release.js

@@ -38,7 +38,7 @@ describe("test/jetstream.js", function() {
     this.timeout(20 * 60 * 1000);
     [
         "-mc",
-        "-mc keep_fargs=false,passes=3,pure_getters,unsafe,unsafe_comps,unsafe_math,unsafe_proto",
+        "-mc keep_fargs=false,passes=3,unsafe,unsafe_comps,unsafe_math,unsafe_proto",
     ].forEach(function(options) {
         it("Should pass with options " + options, function(done) {
             var args = options.split(/ /);