Don't mangle computed properties with keep_quoted (#1058)

* Preserve computed attributes when mangling with keep_quoted

There were various failures when using computed properties with property mangling enabled with `keep_quoted`:

```js
// keep_quoted: true

let prop = '_foo';
let o = {
  [prop]: 'bar'
};
console.log(o[id('_foo')]);

// - - -

let prop = '_foo';
let o = {
  [prop]() { return 'bar' }
};
console.log(o[id('_foo')]());

// - - -

let prop = '_foo';
let o = {
  get [prop]() { return 'bar' }
};
console.log(o[id('_foo')]);
```

```js
// keep_quoted: 'strict'

let prop = '_foo';
let o = {
  [prop]: 'bar'
};
console.log(o[id('_foo')]);
```

* Add tests for strict/loose keep_quotes actually reserving names

* Unskip tests

lib/compress/index.js

@@ -4485,12 +4485,15 @@ function lift_key(self, compressor) {
         if (self.key.value == "constructor"
             && compressor.parent() instanceof AST_Class) return self;
         if (self instanceof AST_ObjectKeyVal) {
+            self.quote = self.key.quote;
             self.key = self.key.value;
         } else if (self instanceof AST_ClassProperty) {
+            self.quote = self.key.quote;
             self.key = make_node(AST_SymbolClassProperty, self.key, {
                 name: self.key.value
             });
         } else {
+            self.quote = self.key.quote;
             self.key = make_node(AST_SymbolMethod, self.key, {
                 name: self.key.value
             });

lib/propmangle.js

@@ -218,7 +218,7 @@ function mangle_properties(ast, options) {
     var names_to_mangle = new Set();
     var unmangleable = new Set();
 
-    var keep_quoted_strict = options.keep_quoted === "strict";
+    var keep_quoted = !!options.keep_quoted;
 
     // step 1: find candidates to mangle
     ast.walk(new TreeWalker(function(node) {
@@ -231,13 +231,12 @@ function mangle_properties(ast, options) {
         ) {
             // handled by mangle_private_properties
         } else if (node instanceof AST_ObjectKeyVal) {
-            if (typeof node.key == "string" &&
-                (!keep_quoted_strict || !node.quote)) {
+            if (typeof node.key == "string" && (!keep_quoted || !node.quote)) {
                 add(node.key);
             }
         } else if (node instanceof AST_ObjectProperty) {
             // setter or getter, since KeyVal is handled above
-            if (!keep_quoted_strict || !node.key.end.quote) {
+            if (!keep_quoted || !node.quote) {
                 add(node.key.name);
             }
         } else if (node instanceof AST_Dot) {
@@ -250,11 +249,11 @@ function mangle_properties(ast, options) {
                 declared = !(root.thedef && root.thedef.undeclared);
             }
             if (declared &&
-                (!keep_quoted_strict || !node.quote)) {
+                (!keep_quoted || !node.quote)) {
                 add(node.property);
             }
         } else if (node instanceof AST_Sub) {
-            if (!keep_quoted_strict) {
+            if (!keep_quoted) {
                 addStrings(node.property, add);
             }
         } else if (node instanceof AST_Call
@@ -276,20 +275,19 @@ function mangle_properties(ast, options) {
         ) {
             // handled by mangle_private_properties
         } else if (node instanceof AST_ObjectKeyVal) {
-            if (typeof node.key == "string" &&
-                (!keep_quoted_strict || !node.quote)) {
+            if (typeof node.key == "string" && (!keep_quoted || !node.quote)) {
                 node.key = mangle(node.key);
             }
         } else if (node instanceof AST_ObjectProperty) {
             // setter, getter, method or class field
-            if (!keep_quoted_strict || !node.key.end.quote) {
+            if (!keep_quoted || !node.quote) {
                 node.key.name = mangle(node.key.name);
             }
         } else if (node instanceof AST_Dot) {
-            if (!keep_quoted_strict || !node.quote) {
+            if (!keep_quoted || !node.quote) {
                 node.property = mangle(node.property);
             }
-        } else if (!options.keep_quoted && node instanceof AST_Sub) {
+        } else if (!keep_quoted && node instanceof AST_Sub) {
             node.property = mangleStrings(node.property);
         } else if (node instanceof AST_Call
             && node.expression.print_to_string() == "Object.defineProperty") {