[parser|js-perf-test] Disable compilation cache in the parsing microbrenchmarks.

Evalling multiple long strings makes compilation cache the bottleneck: See
https://bugs.chromium.org/p/v8/issues/detail?id=6779 for more information.

BUG=v8:6779

Change-Id: I0014b1aca1258a643cbeb441a82707b163f8166d
Reviewed-on: https://chromium-review.googlesource.com/649146Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47801}

test/js-perf-test/JSTests.json

@@ -617,6 +617,7 @@
       "name": "Parsing",
       "path": ["Parsing"],
       "main": "run.js",
+      "flags": ["--no-compilation-cache", "--allow-natives-syntax"],
       "resources": [ "comments.js"],
       "results_regexp": "^%s\\-Parsing\\(Score\\): (.+)$",
       "tests": [

test/js-perf-test/Parsing/comments.js

@@ -4,10 +4,6 @@
 
 const iterations = 100;
 
-// Each benchmark.run is surrounded by a loop of 100. To generate the right
-// amount of test cases, we just need to know this constant.
-const fixed_iterations_by_runner = 100;
-
 new BenchmarkSuite('OneLineComment', [1000], [
   new Benchmark('OneLineComment', false, true, iterations, Run, OneLineCommentSetup)
 ]);
@@ -20,44 +16,26 @@ new BenchmarkSuite('MultiLineComment', [1000], [
   new Benchmark('MultiLineComment', false, true, iterations, Run, MultiLineCommentSetup)
 ]);
 
-let codes;
-let ix;
-
-// Functions generating the code snippets which the actual test will eval. The
-// snippets need to be different for each iteration, so that we won't hit the
-// compilation cache.
+let code;
 
 function OneLineCommentSetup() {
-  codes = [];
-  ix = 0;
-  for (let i = 0; i < iterations * fixed_iterations_by_runner; ++i) {
-    let code = "//" + " This is a comment... ".repeat(600) + i;
-    codes.push(code);
-  }
+  code = "//" + " This is a comment... ".repeat(600);
+  %FlattenString(code);
 }
 
 function OneLineCommentsSetup() {
-  codes = [];
-  ix = 0;
-  for (let i = 0; i < iterations * fixed_iterations_by_runner; ++i) {
-    let code = "// This is a comment.\n".repeat(600) + "\n//" + i;
-    codes.push(code);
-  }
+  code = "// This is a comment.\n".repeat(600);
+  %FlattenString(code);
 }
 
 function MultiLineCommentSetup() {
-  codes = [];
-  ix = 0;
-  for (let i = 0; i < iterations * fixed_iterations_by_runner; ++i) {
-    let code = "/*" + " This is a comment... ".repeat(600) + "*/" + i;
-    codes.push(code);
-  }
+  code = "/*" + " This is a comment... ".repeat(600) + "*/";
+  %FlattenString(code);
 }
 
 function Run() {
-   if (ix >= codes.length) {
-    throw new Error("Not enough test data");
+  if (code == undefined) {
+    throw new Error("No test data");
   }
-  eval(codes[ix]);
-  ++ix;
+  eval(code);
 }