Introduce mkgrokdump to update tools/v8heapconst.py.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 8daba55e4d6847575df44f16e2387819a3926b88..7d36a214cd73fdb7c56b680c1eae404b89b0b012 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -142,6 +142,7 @@ if (v8_enable_v8_checks == "") {
 is_target_simulator = target_cpu != v8_target_cpu
 
 v8_generated_peephole_source = "$target_gen_dir/bytecode-peephole-table.cc"
+v8_generated_heap_constants = "$target_gen_dir/v8heapconst.py"
 v8_random_seed = "314159265"
 v8_toolset_for_shell = "host"
 
@@ -2666,6 +2667,28 @@ v8_executable("mkpeephole") {
   ]
 }
 
+v8_executable("mkgrokdump") {

[Michael Achenbach, 2017/04/11 09:45:54]

Note that due to GN's nature, this target will be built everywhere where all or
no target is specified. Also in Chromium.

Maybe also add it to:
https://cs.chromium.org/chromium/build/scripts/slave/recipe_modules/archive/r...

[Yang, 2017/04/11 09:57:20]

Acknowledged.

+  # mkgrokdump is used to create tools/v8heapconst.py.
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+
+  sources = [
+    "tools/mkgrokdump.cc",
+  ]
+
+  configs = [
+    ":external_config",
+    ":internal_config",
+  ]
+
+  deps = [
+    ":v8",
+    ":v8_libbase",
+    ":v8_libplatform",
+    "//build/config/sanitizers:deps",
+    "//build/win:default_exe_manifest",
+  ]
+}
+
 ###############################################################################
 # Public targets
 #