[test] Add back lsan leak detection

gni/isolate.gni

 # Copyright 2016 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/sanitizers/sanitizers.gni")
 import("//third_party/icu/config.gni")
 import("v8.gni")
 
 declare_args() {
   # Sets the test isolation mode (noop|prepare|check).
@@ skipping 43 matching lines @@
           "$root_out_dir/$name.isolated.state",
         ]
       }
 
       # Translate gn to gyp variables.
       if (is_asan) {
         asan = "1"
       } else {
         asan = "0"
       }
+      if (is_lsan) {
+        lsan = "1"
+      } else {
+        lsan = "0"
+      }
       if (is_msan) {
         msan = "1"
       } else {
         msan = "0"
       }
       if (is_tsan) {
         tsan = "1"
       } else {
         tsan = "0"
       }
@@ skipping 77 matching lines @@
         "cfi_vptr=$cfi_vptr",
         "--config-variable",
         "gcmole=$gcmole",
         "--config-variable",
         "has_valgrind=$has_valgrind",
         "--config-variable",
         "icu_use_data_file_flag=$icu_use_data_file_flag",
         "--config-variable",
         "is_gn=1",
         "--config-variable",
+        "lsan=$lsan",
+        "--config-variable",
         "msan=$msan",
         "--config-variable",
         "tsan=$tsan",
         "--config-variable",
         "coverage=0",
         "--config-variable",
         "sanitizer_coverage=0",
         "--config-variable",
         "component=$component",
         "--config-variable",
@@ skipping 13 matching lines @@
         ]
       } else {
         args += [
           "--config-variable",
           "msvs_version=0",
         ]
       }
     }
   }
 }