[es6] implement spread calls

test/js-perf-test/JSTests.json

 {
   "name": "JSTests",
   "run_count": 5,
   "run_count_android_arm": 3,
   "run_count_android_arm64": 3,
   "units": "score",
   "total": true,
   "resources": ["base.js"],
   "tests": [
     {
+      "name": "SpreadCalls",
+      "path": ["SpreadCalls"],
+      "main": "run.js",
+      "resources": ["spreadcalls.js"],
+      "flags": ["--harmony-spreadcalls"],
+      "run_count": 5,
+      "units": "score",
+      "results_regexp": "^%s\\-SpreadCalls\\(Score\\): (.+)$",
+      "tests": [
+        {"name": "Call-Sum"},

[Michael Achenbach, 2015/04/10 10:04:20]

What is actually printed is (exemplified):
Call-SpreadCalls(Score): 123
CallMethod-SpreadCalls(Score): 123
CallNew-SpreadCalls(Score): 123

Therefore the perf runner fails to gather these results as it looks for e.g.
Call-Sum-SpreadCalls.

Repro:
make x64.release
tools/run_perf.py --arch x64 test/js-perf-test/JSTests.json

+        {"name": "CallMethod-Sum"},
+        {"name": "CallNew-Sum"}
+      ]
+    },
+    {
       "name": "Classes",
       "path": ["Classes"],
       "main": "run.js",
       "resources": ["super.js", "default-constructor.js"],
       "flags": ["--harmony-classes"],
       "results_regexp": "^%s\\-Classes\\(Score\\): (.+)$",
       "tests": [
         {"name": "Super"},
         {"name": "DefaultConstructor"}
       ]
@@ skipping 54 matching lines @@
       "results_regexp": "^%s\\-Templates\\(Score\\): (.+)$",
       "total": true,
       "tests": [
         {"name": "Untagged"},
         {"name": "LargeUntagged"},
         {"name": "Tagged"}
       ]
     }
   ]
 }