Non-functional. Rationalizations enabling future generalizations:

- Use much simpler method to update implicit array sizes.
  The previous overly complicated method was error prone.
- Rationalize all use of unsized arrays.
- Combine decorations when generating SPIR-V, to simplify
  adding extensions.

glslang/Include/intermediate.h

@@ -729,7 +729,11 @@ enum TOperator {
     // Array operators
     //
 
-    EOpArrayLength,      // "Array" distinguishes from length(v) built-in function, but it applies to vectors and matrices as well.
+    // Can apply to arrays, vectors, or matrices.
+    // Can be decomposed to a constant at compile time, but this does not always happen,
+    // due to link-time effects. So, consumer can expect either a link-time sized or
+    // run-time sized array.
+    EOpArrayLength,
 
     //
     // Image operations