Fix typo

Change-Id: I5b15e16c140dde600e83e4f48e2902963e948b46
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/114560
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Auto-Submit: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: David Neto <dneto@google.com>

src/tint/source.h

@@ -79,7 +79,7 @@ class Source {
         /// 0 represents no column information.
         size_t column = 0;
 
-        /// Returns true of `this` location is lexicographically less than `rhs`
+        /// Returns true if `this` location is lexicographically less than `rhs`
         /// @param rhs location to compare against
         /// @returns true if `this` < `rhs`
         inline bool operator<(const Source::Location& rhs) {