Respect quote style in object literals

The option added in fbbaa42ee5 wasn't
being respected inside object literals, so quoted property names would
still be stripped out with this option.

This is mostly a corner-case, but useful when the output is passed to
something like the Closure compiler, where quoted property names can be
used to prevent mangling.

bin/uglifyjs

@@ -69,7 +69,7 @@ You need to pass an argument to this option to specify the name that your module
     .describe("quotes", "Quote style (0 - auto, 1 - single, 2 - double, 3 - original)")
     .describe("reserved-file", "File containing reserved names")
     .describe("reserve-domprops", "Make (most?) DOM properties reserved for --mangle-props")
-    .describe("mangle-props", "Mangle property names")
+    .describe("mangle-props", "Mangle property names (0 - disabled, 1 - mangle all properties, 2 - mangle unquoted properies)")
     .describe("mangle-regex", "Only mangle property names matching the regex")
     .describe("name-cache", "File to hold mangled names mappings")
     .describe("pure-funcs", "List of functions that can be safely removed if their return value is not used")
@@ -125,7 +125,6 @@ You need to pass an argument to this option to specify the name that your module
     .boolean("noerr")
     .boolean("bare-returns")
     .boolean("keep-fnames")
-    .boolean("mangle-props")
     .boolean("reserve-domprops")
 
     .wrap(80)
@@ -213,12 +212,24 @@ if (ARGS.quotes === true) {
     ARGS.quotes = 3;
 }
 
+if (ARGS.mangle_props === true) {
+    ARGS.mangle_props = 1;
+} else if (ARGS.mangle_props === "unquoted") {
+    ARGS.mangle_props = 2;
+}
+
 var OUTPUT_OPTIONS = {
     beautify    : BEAUTIFY ? true : false,
     preamble    : ARGS.preamble || null,
     quote_style : ARGS.quotes != null ? ARGS.quotes : 0
 };
 
+if (ARGS.mangle_props == 2) {
+    OUTPUT_OPTIONS.keep_quoted_props = true;
+    if (COMPRESS && !("properties" in COMPRESS))
+        COMPRESS.properties = false;
+}
+
 if (ARGS.screw_ie8) {
     if (COMPRESS) COMPRESS.screw_ie8 = true;
     if (MANGLE) MANGLE.screw_ie8 = true;
@@ -401,10 +412,11 @@ async.eachLimit(files, 1, function (file, cb) {
         }
 
         TOPLEVEL = UglifyJS.mangle_properties(TOPLEVEL, {
-            reserved   : reserved,
-            cache      : cache,
-            only_cache : !ARGS.mangle_props,
-            regex      : regex
+            reserved      : reserved,
+            cache         : cache,
+            only_cache    : !ARGS.mangle_props,
+            regex         : regex,
+            ignore_quoted : ARGS.mangle_props == 2
         });
         writeNameCache("props", cache);
     })();