[platform] Spell Fuchsia correctly in comments

Change-Id: I7e73b1f9cd81c91b5399f1cd01eb3bd6766025d5
Reviewed-on: https://chromium-review.googlesource.com/c/1490601Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Nathan Rogers <nathanrogers@google.com>
Cr-Commit-Position: refs/heads/master@{#59893}

src/base/platform/platform-posix.cc

@@ -269,7 +269,7 @@ void* OS::GetRandomMmapAddr() {
   return reinterpret_cast<void*>(raw_addr);
 }
 
-// TODO(bbudge) Move Cygwin and Fuschia stuff into platform-specific files.
+// TODO(bbudge) Move Cygwin and Fuchsia stuff into platform-specific files.
 #if !V8_OS_CYGWIN && !V8_OS_FUCHSIA
 // static
 void* OS::Allocate(void* address, size_t size, size_t alignment,