Added optional sharding for browser builders in the annotated steps scripts

tools/bots/compiler.py

Index: tools/bots/compiler.py
diff --git a/tools/bots/compiler.py b/tools/bots/compiler.py
index f51520ab43a7267926ffb996aa0a6206157b9794..7e60dddaf75c6c43fdbfe358873ec19d64ade2b9 100644
--- a/tools/bots/compiler.py
+++ b/tools/bots/compiler.py
@@ -22,7 +22,7 @@ import bot
 DART2JS_BUILDER = (
     r'dart2js-(linux|mac|windows)(-(jsshell))?-(debug|release)(-(checked|host-checked))?(-(host-checked))?(-(minified))?-?(\d*)-?(\d*)')
 WEB_BUILDER = (
-    r'dart2js-(ie9|ie10|ff|safari|chrome|opera)-(win7|win8|mac|linux)(-(all|html))?')
+    r'dart2js-(ie9|ie10|ff|safari|chrome|opera)-(win7|win8|mac|linux)(-(all|html))?(-(\d+)-(\d+))?')
 
 
 def GetBuildInfo(builder_name, is_buildbot):
@@ -49,6 +49,8 @@ def GetBuildInfo(builder_name, is_buildbot):
     system = web_pattern.group(2)
     mode = 'release'
     test_set = web_pattern.group(4)
+    shard_index = web_pattern.group(6)
+    total_shards = web_pattern.group(7)
   elif dart2js_pattern:
     compiler = 'dart2js'
     system = dart2js_pattern.group(1)