Don't create Static memories larger than the Tunables' static bound size.

lib/environ/src/module.rs

@@ -54,24 +54,25 @@ impl MemoryStyle {
     /// Decide on an implementation style for the given `Memory`.
     pub fn for_memory(memory: Memory, tunables: &Tunables) -> (Self, u64) {
         if let Some(maximum) = memory.maximum {
-            // A heap with a declared maximum is prepared to be used with
-            // threads and therefore be immovable, so make it static.
-            (
+            if maximum <= tunables.static_memory_bound {
+                // A heap with a declared maximum can be immovable, so make
+                // it static.
+                return (
                     MemoryStyle::Static {
-                    bound: cmp::max(tunables.static_memory_bound, maximum),
+                        bound: tunables.static_memory_bound,
                     },
                     tunables.static_memory_offset_guard_size,
-            )
-        } else {
-            // A heap without a declared maximum is likely to want to be small
-            // at least some of the time, so make it dynamic.
+                );
+            }
+        }
+
+        // Otherwise, make it dynamic.
         (
             MemoryStyle::Dynamic,
             tunables.dynamic_memory_offset_guard_size,
         )
     }
 }
-}
 
 /// A WebAssembly linear memory description along with our chosen style for
 /// implementing it.