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.

test/mocha/minify.js

@@ -7,5 +7,56 @@ describe("minify", function() {
         var result = Uglify.minify(js, {fromString: true});
         assert.strictEqual(result.code, 'function foo(n){return n?3:7}');
     });
-});
 
+    describe("keep_quoted_props", function() {
+        it("Should preserve quotes in object literals", function() {
+            var js = 'var foo = {"x": 1, y: 2, \'z\': 3};';
+            var result = Uglify.minify(js, {
+                fromString: true, output: {
+                    keep_quoted_props: true
+                }});
+            assert.strictEqual(result.code, 'var foo={"x":1,y:2,"z":3};');
+        });
+
+        it("Should preserve quote styles when quote_style is 3", function() {
+            var js = 'var foo = {"x": 1, y: 2, \'z\': 3};';
+            var result = Uglify.minify(js, {
+                fromString: true, output: {
+                    keep_quoted_props: true,
+                    quote_style: 3
+                }});
+            assert.strictEqual(result.code, 'var foo={"x":1,y:2,\'z\':3};');
+        });
+
+        it("Should not preserve quotes in object literals when disabled", function() {
+            var js = 'var foo = {"x": 1, y: 2, \'z\': 3};';
+            var result = Uglify.minify(js, {
+                fromString: true, output: {
+                    keep_quoted_props: false,
+                    quote_style: 3
+                }});
+            assert.strictEqual(result.code, 'var foo={x:1,y:2,z:3};');
+        });
+    });
+
+    describe("mangleProperties", function() {
+        it("Shouldn't mangle quoted properties", function() {
+            var js = 'a["foo"] = "bar"; a.color = "red"; x = {"bar": 10};';
+            var result = Uglify.minify(js, {
+                fromString: true,
+                compress: {
+                    properties: false
+                },
+                mangleProperties: {
+                    ignore_quoted: true
+                },
+                output: {
+                    keep_quoted_props: true,
+                    quote_style: 3
+                }
+            });
+            assert.strictEqual(result.code,
+                    'a["foo"]="bar",a.a="red",x={"bar":10};');
+        });
+    });
+});