https://bugs.webkit.org/show_bug.cgi?id=95931

Reviewed by Adam Barth.

Remove PlatformString.h

Source/WebCore:

* GNUmakefile.list.am:
* Modules/filesystem/AsyncFileWriter.h:
* Modules/filesystem/DOMFilePath.h:
* Modules/filesystem/DOMFileSystemBase.h:
* Modules/filesystem/DirectoryEntry.h:
* Modules/filesystem/DirectoryEntrySync.h:
* Modules/filesystem/DirectoryReader.h:
* Modules/filesystem/DirectoryReaderBase.h:
* Modules/filesystem/DirectoryReaderSync.h:
* Modules/filesystem/EntryBase.cpp:
* Modules/filesystem/EntrySync.h:
* Modules/filesystem/FileEntrySync.h:
* Modules/filesystem/FileSystemCallbacks.h:
* Modules/filesystem/LocalFileSystem.h:
* Modules/geolocation/GeolocationError.h:
* Modules/geolocation/Geoposition.h:
* Modules/geolocation/PositionError.h:
* Modules/indexeddb/IDBAny.h:
* Modules/indexeddb/IDBDatabaseBackendInterface.h:
* Modules/indexeddb/IDBDatabaseCallbacks.h:
* Modules/indexeddb/IDBDatabaseCallbacksImpl.h:
* Modules/in...