Fuchsia: Revert observatory inclusion again

runtime/bin/BUILD.gn

Index: runtime/bin/BUILD.gn
diff --git a/runtime/bin/BUILD.gn b/runtime/bin/BUILD.gn
index f8428bd4ae6ca84f3f78c9802184ab18910c7c09..07b9b1707e6c6a10e699d58bde1c264bcb645f2a 100644
--- a/runtime/bin/BUILD.gn
+++ b/runtime/bin/BUILD.gn
@@ -607,35 +607,37 @@ template("dart_executable") {
   }
 }
 
-dart_executable("dart") {
-  extra_deps = [
-    "..:libdart",
-    ":dart_snapshot_cc",
-    "../observatory:standalone_observatory_archive",
-  ]
-  extra_sources = [ "builtin_nolib.cc" ]
-}
+if (!defined(is_fuchsia) || !is_fuchsia) {
+  dart_executable("dart") {
+    extra_deps = [
+      "..:libdart",
+      ":dart_snapshot_cc",
+      "../observatory:standalone_observatory_archive",
+    ]
+    extra_sources = [ "builtin_nolib.cc" ]
+  }
 
-dart_executable("dart_noopt") {
-  extra_configs = [ "..:dart_precompiler_config" ]
-  extra_deps = [
-    "..:libdart_noopt",
-    ":dart_snapshot_cc",
-    "../observatory:standalone_observatory_archive",
-  ]
-  extra_sources = [ "builtin_nolib.cc" ]
-}
+  dart_executable("dart_noopt") {
+    extra_configs = [ "..:dart_precompiler_config" ]
+    extra_deps = [
+      "..:libdart_noopt",
+      ":dart_snapshot_cc",
+      "../observatory:standalone_observatory_archive",
+    ]
+    extra_sources = [ "builtin_nolib.cc" ]
+  }
 
-dart_executable("dart_precompiled_runtime") {
-  extra_configs = [ "..:dart_precompiled_runtime_config" ]
-  extra_deps = [
-    "..:libdart_precompiled_runtime",
-    "../observatory:standalone_observatory_archive",
-  ]
-  extra_sources = [
-    "builtin_nolib.cc",
-    "snapshot_empty.cc",
-  ]
+  dart_executable("dart_precompiled_runtime") {
+    extra_configs = [ "..:dart_precompiled_runtime_config" ]
+    extra_deps = [
+      "..:libdart_precompiled_runtime",
+      "../observatory:standalone_observatory_archive",
+    ]
+    extra_sources = [
+      "builtin_nolib.cc",
+      "snapshot_empty.cc",
+    ]
+  }
 }
 
 dart_executable("dart_bootstrap") {