Fix a couple of google3 build issues

We were missing an include for uint32_t, and a forward declaration.

Change-Id: I4a2eed757364e335e12d14aaeda18fc7aafb2886
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/93261
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: James Price <jrprice@google.com>

src/dawn/common/Numeric.h

@@ -15,6 +15,7 @@
 #ifndef SRC_DAWN_COMMON_NUMERIC_H_
 #define SRC_DAWN_COMMON_NUMERIC_H_
 
+#include <cstdint>
 #include <limits>
 #include <type_traits>
 

src/dawn/utils/WireHelper.h

@@ -21,6 +21,8 @@
 
 #include "dawn/webgpu_cpp.h"
 
+struct DawnProcTable;
+
 namespace utils {
 
 class WireHelper {