[ObjC] Typos and comment improvements.
diff --git a/objectivec/GPBDescriptor_PackagePrivate.h b/objectivec/GPBDescriptor_PackagePrivate.h
index 467504f..b3d6730 100644
--- a/objectivec/GPBDescriptor_PackagePrivate.h
+++ b/objectivec/GPBDescriptor_PackagePrivate.h
@@ -155,9 +155,9 @@
   // breaking change in the runtime.
   GPBDescriptorInitializationFlag_UsesClassRefs     = 1 << 2,
 
-  // This flag is used to indicate that the generated sources already containg
+  // This flag is used to indicate that the generated sources already contain
   // the `GPBFieldClearHasIvarOnZero` flag and it doesn't have to be computed
-  // at startup, this allows older generated code to still work with the
+  // at startup. This allows older generated code to still work with the
   // current runtime library.
   GPBDescriptorInitializationFlag_Proto3OptionalKnown = 1 << 3,
 };