Fix minor typo in instance-type.h

Change-Id: Icccd7d8d0701ddbf9fb5088f5a47caa992f1b1e2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2120296Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68861}

src/objects/instance-type.h

@@ -154,7 +154,7 @@ enum InstanceType : uint16_t {
 };
 
 // This constant is defined outside of the InstanceType enum because the
-// string instance types are sparce and there's no such a string instance type.
+// string instance types are sparse and there's no such string instance type.
 // But it's still useful for range checks to have such a value.
 constexpr InstanceType LAST_STRING_TYPE =
     static_cast<InstanceType>(FIRST_NONSTRING_TYPE - 1);