Rerun limit queries if a partial index is available. (#6301)

This is porting firebase/firebase-android-sdk#3657 to
the Web SDK. The majority of the code was ported as a part of other PRs such as
#6153.

The only thing remaining is to port the tests in SQLiteLocalStoreTest.java which
will be done as a part of #6261.

Author: ehsannas

packages/firestore/src/local/query_engine.ts

@@ -154,7 +154,7 @@ export class QueryEngine {
           return null;
         }
 
-        if (indexType === IndexType.PARTIAL) {
+        if (query.limit !== null && indexType === IndexType.PARTIAL) {
           // We cannot apply a limit for targets that are served using a partial
           // index. If a partial index will be used to serve the target, the
           // query may return a superset of documents that match the target
@@ -301,7 +301,7 @@ export class QueryEngine {
    * Determines if a limit query needs to be refilled from cache, making it
    * ineligible for index-free execution.
    *
-   * @param query The query.
+   * @param query - The query.
    * @param sortedPreviousResults - The documents that matched the query when it
    * was last synchronized, sorted by the query's comparator.
    * @param remoteKeys - The document keys that matched the query at the last