[JSC] Wrong names set for anonymous classes from static class fields in some cases

[Caio Lima]

The following example is setting the wrong name for anonymous classes:

```
class C { static InnerClass = class { static f = this.name; } }
 
print(C.InnerClass.name); // prints “”, but should print “InnerClass”
```

The following example does it correctly:

```
class C { static InnerClass = class { static f; } }
 
print(C.InnerClass.name); // prints “InnerClass”
```

Both Firefox and Chrome are returning “InnerClass” for both examples. This example came up from a spec bug pointed out on https://github.com/tc39/ecma262/pull/1668#issuecomment-608189621.

[Radar WebKit Bug Importer]

<rdar://problem/77963278>