Drop all console statements properly

Because the base reference can be an member expression as well, we have to dig a bit deeper to find the leftmost base reference.

Fixes #451

test/compress/drop-console.js

@@ -0,0 +1,24 @@
+drop_console_1: {
+    options = {};
+    input: {
+        console.log('foo');
+        console.log.apply(console, arguments);
+    }
+    expect: {
+        console.log('foo');
+        console.log.apply(console, arguments);
+    }
+}
+
+drop_console_1: {
+    options = { drop_console: true };
+    input: {
+        console.log('foo');
+        console.log.apply(console, arguments);
+    }
+    expect: {
+        // with regular compression these will be stripped out as well
+        void 0;
+        void 0;
+    }
+}