[test] Reduce time spent on js-perf tests and fix timeouts.

Strings takes a considerate amount of time and times out on
many platforms. Generally the iterations need to be reduced
to free resources.

NOTRY=true
TBR=hablich@chromium.org

Review-Url: https://codereview.chromium.org/2374393002
Cr-Commit-Position: refs/heads/master@{#39856}

test/js-perf-test/JSTests.json

 {
   "name": "JSTests",
-  "run_count": 5,
-  "run_count_android_arm": 3,
-  "run_count_android_arm64": 3,
+  "run_count": 3,
+  "run_count_android_arm": 1,
+  "run_count_android_arm64": 1,
   "timeout": 120,
   "units": "score",
   "total": true,
@@ -45,7 +45,6 @@
       "path": ["RestParameters"],
       "main": "run.js",
       "resources": ["rest.js"],
-      "run_count": 5,
       "units": "score",
       "results_regexp": "^%s\\-RestParameters\\(Score\\): (.+)$",
       "tests": [
@@ -57,7 +56,6 @@
       "path": ["SpreadCalls"],
       "main": "run.js",
       "resources": ["spreadcalls.js"],
-      "run_count": 5,
       "units": "score",
       "results_regexp": "^%s\\-SpreadCalls\\(Score\\): (.+)$",
       "tests": [
@@ -119,6 +117,8 @@
       "main": "run.js",
       "resources": ["harmony-string.js"],
       "results_regexp": "^%s\\-Strings\\(Score\\): (.+)$",
+      "run_count": 1,
+      "timeout": 240,
       "tests": [
         {"name": "StringFunctions"}
       ]
@@ -146,7 +146,6 @@
       "path": ["Templates"],
       "main": "run.js",
       "resources": ["templates.js"],
-      "run_count": 5,
       "units": "score",
       "results_regexp": "^%s\\-Templates\\(Score\\): (.+)$",
       "total": true,
@@ -201,9 +200,6 @@
       "main": "run.js",
       "resources": ["keys.js"],
       "results_regexp": "^%s\\-Keys\\(Score\\): (.+)$",
-      "run_count": 3,
-      "run_count_android_arm": 2,
-      "run_count_android_arm64": 2,
       "tests": [
         {"name": "Object.keys()"},
         {"name": "for-in"},