Vulkan: Always request all VkSurfaceKHR-related extensions

The backend had a "requiredInstanceExtensions" parameter to device
creation so that we could request the right instance extensions to
support swapchains. When we have dawn_native::Instance we don't want to
require this information before we can use the Vulkan backend. Instead
we make the backend always require all VkSurfaceKHR extensions. This
should be safe because these extensions basically enable copying a
struct into an opaque VkSurfaceKHR object and not much else.

BUG=dawn:29

Change-Id: I7fc5426f5770b65bb35f02793a1319eb0653782c
Reviewed-on: https://dawn-review.googlesource.com/c/3662
Reviewed-by: Stephen White <senorblanco@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

src/utils/VulkanBinding.cpp

@@ -28,13 +28,7 @@ namespace utils {
             glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
         }
         dawnDevice CreateDevice() override {
-            uint32_t extensionCount = 0;
-            const char** glfwInstanceExtensions =
-                glfwGetRequiredInstanceExtensions(&extensionCount);
-            std::vector<const char*> requiredExtensions(glfwInstanceExtensions,
-                                                        glfwInstanceExtensions + extensionCount);
-
-            mDevice = dawn_native::vulkan::CreateDevice(requiredExtensions);
+            mDevice = dawn_native::vulkan::CreateDevice();
             return mDevice;
         }
         uint64_t GetSwapChainImplementation() override {