Fix cr SKPs naming

 #crskps

BUG=skia:
BUG=skia:3574

NOTRY=true

TBR=borenet

Review URL: https://codereview.chromium.org/1044193003
diff --git a/tools/skp/webpages_playback.py b/tools/skp/webpages_playback.py
index 67c84ae..7fbb372 100644
--- a/tools/skp/webpages_playback.py
+++ b/tools/skp/webpages_playback.py
@@ -388,7 +388,10 @@
     # /path/to/http___mobile_news_sandbox_pt0 -> http___mobile_news_sandbox_pt0
     _, webpage = os.path.split(site)
     # http___mobile_news_sandbox_pt0 -> mobile_news_sandbox_pt0
-    webpage = webpage.lstrip('http___').lstrip('https___')
+    if webpage.startswith('http___'):
+      webpage = webpage[7:]
+    elif webpage.startswith('https___'):
+      webpage = webpage[8:]
     # /path/to/skia_yahooanswers_desktop.py -> skia_yahooanswers_desktop.py
     ps_filename = os.path.basename(page_set)
     # http___mobile_news_sandbox -> pagesetprefix_http___mobile_news_sandbox