Convert narrowing casts from T{} to static_cast<T>(): url/

The style guide encourages use of T{}-style casts under the assumption
that the compiler will warn about narrowing.  This warning is currently
disabled; enabling it requires fixing up the cases that narrow.

Bug: 1216696
Change-Id: I9dc6132462fb8f02b197bf688b690b308e9cb4da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2946568
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#890410}

url/url_canon_internal.cc

@@ -427,7 +427,7 @@ int _itow_s(int value, char16_t* buffer, size_t size_in_chars, int radix) {
   }
 
   for (int i = 0; i < written; ++i) {
-    buffer[i] = char16_t{temp[i]};
+    buffer[i] = static_cast<char16_t>(temp[i]);
   }
   buffer[written] = '\0';
   return 0;