Require spec/suite property keys to be strings, not just anything that's cloneable and serializable

This matches the jsdoc.

lib/jasmine-core/jasmine.js

@@ -849,8 +849,11 @@ getJasmineRequireObj().Spec = function(j$) {
       // Key and value will eventually be cloned during reporting. The error
       // thrown at that point if they aren't cloneable isn't very helpful.
       // Throw a better one now.
-      j$.private.util.assertReporterCloneable(key, 'Key');
+      if (!j$.private.isString(key)) {
+        throw new Error('Key must be a string');
+      }
       j$.private.util.assertReporterCloneable(value, 'Value');
+
       this.#executionState.properties = this.#executionState.properties || {};
       this.#executionState.properties[key] = value;
     }
@@ -10851,8 +10854,11 @@ getJasmineRequireObj().Suite = function(j$) {
       // Key and value will eventually be cloned during reporting. The error
       // thrown at that point if they aren't cloneable isn't very helpful.
       // Throw a better one now.
-      j$.private.util.assertReporterCloneable(key, 'Key');
+      if (!j$.private.isString(key)) {
+        throw new Error('Key must be a string');
+      }
       j$.private.util.assertReporterCloneable(value, 'Value');
+
       this.#result.properties = this.#result.properties || {};
       this.#result.properties[key] = value;
     }