[gjs] coverage: Don't replace existing statistics with new ones

[Jasper St. Pierre <jstpierre src gnome org>]

commit 8d8660d982be701f39898d5bac01f1bdd62a3b84
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Mon Feb 3 14:42:07 2014 -0500

    coverage: Don't replace existing statistics with new ones
    
    The existing code here relies on pendingFiles getting modified, which
    is a bit tricky and won't work in our new prefix system. Instead, just
    make ensureStatisticsFor return an existing object if it exists already.

 modules/coverage.js |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)
---
diff --git a/modules/coverage.js b/modules/coverage.js
index 8ec96a2..845a9e5 100644
--- a/modules/coverage.js
+++ b/modules/coverage.js
@@ -652,15 +652,14 @@ function CoverageStatisticsContainer(files) {
     let coveredFiles = {};
 
     function ensureStatisticsFor(filename) {
-        let statistics = _createStatisticsForFoundFilename(filename, pendingFiles);
-        if (statistics)
-            coveredFiles[filename] = statistics;
+        if (!coveredFiles[filename])
+            coveredFiles[filename] = _createStatisticsForFoundFilename(filename, pendingFiles);
+        return coveredFiles[filename];
     }
 
     this.fetchStatistics = function(filename) {
-        ensureStatisticsFor(filename);
-        let statistics = coveredFiles[filename];
-        if (statistics === undefined)
+        let statistics = ensureStatisticsFor(filename);
+        if (statistics === null)
             throw new Error('Not tracking statistics for ' + filename);
         return statistics;
     };