Support changing null to false in update-bcd

scripts/update-bcd.test.ts

@@ -893,6 +893,33 @@ describe("BCD updater", () => {
       );
     });
 
+    it("detects updates in statements with null values", () => {
+      // Both a true and false test result is new information, but null is not.
+      assert.isTrue(
+        hasSupportUpdates(new Map([["80", true]]), [
+          {
+            version_added: null,
+          },
+        ]),
+      );
+
+      assert.isTrue(
+        hasSupportUpdates(new Map([["80", false]]), [
+          {
+            version_added: null,
+          },
+        ]),
+      );
+
+      assert.isFalse(
+        hasSupportUpdates(new Map([["80", null]]), [
+          {
+            version_added: null,
+          },
+        ]),
+      );
+    });
+
     it("detects updates in statements with boolean values", () => {
       assert.isFalse(
         hasSupportUpdates(new Map([["80", false]]), [

scripts/update-bcd.ts

@@ -819,14 +819,18 @@ const skipCurrentBeforeSupport = skip("currentBeforeSupport", ({
  * @param version - A version string.
  * @param hasSupport - An boolean indicating if a test result for the version shows support.
  * @param statements - An array of default statements.
- * @returns A boolean indicating whether default statements indicate support for the version.
+ * @returns A boolean or null indicating whether default statements indicate support for the version.
  */
 const isSupported = (
   version: string,
   hasSupport: boolean,
   statements: SimpleSupportStatement[],
 ) => {
   for (const {version_added, version_removed} of statements) {
+    if (version_added === null) {
+      return null;
+    }
+
     if (version_added === "preview") {
       return false;
     }
@@ -858,7 +862,7 @@ const isSupported = (
  *  Iterates through a BrowserSupportMap and checks each version for possible updates against a set of default statements.
  * @param versionMap - A map of versions and support assertions.
  * @param defaultStatements - An array of default statements.
- * @returns A boolean indicating whether possible updates to the default statments have been detected.
+ * @returns A boolean indicating whether possible updates to the default statements have been detected.
  */
 export const hasSupportUpdates = (
   versionMap: BrowserSupportMap,