Rename shell to v8_shell

BUG=chromium:609107
R=machenbach@chromium.org
LOG=n

Review-Url: https://codereview.chromium.org/1962253002
Cr-Commit-Position: refs/heads/master@{#36138}

BUILD.gn

@@ -2134,7 +2134,7 @@ if ((current_toolchain == host_toolchain && v8_toolset_for_d8 == "host") ||
 }
 
 if ((current_toolchain == host_toolchain && v8_toolset_for_shell == "host") || (current_toolchain == snapshot_toolchain && v8_toolset_for_shell == "host") || (current_toolchain != host_toolchain && v8_toolset_for_shell == "target")) {
-  executable("shell") {
+  executable("v8_shell") {
     sources = [
       "samples/shell.cc",
     ]

samples/samples.gyp

@@ -57,7 +57,7 @@
   },
   'targets': [
     {
-      'target_name': 'shell',
+      'target_name': 'v8_shell',
       'sources': [
         'shell.cc',
       ],