Decode main.js.map during snapshotting.

Pro:
time ./out/debug/deno tests/error_001.ts  3.0s -> 0.4s

Con:
time ./tool/build.py snapshot              33s -> 1m52s
out/debug/gen/snapshot_deno.bin            39M -> 121M

1 files changed, 7 insertions, 7 deletions

diff --git a/libdeno/binding.cc b/libdeno/binding.cc
index 6cf0a7a21..999ccac47 100644
--- a/libdeno/binding.cc
+++ b/libdeno/binding.cc
@@ -521,13 +521,6 @@ void InitializeContext(v8::Isolate* isolate, v8::Local<v8::Context> context,
             .FromJust());
 
   {
-    auto source = deno::v8_str(js_source);
-    CHECK(
-        deno_val->Set(context, deno::v8_str("mainSource"), source).FromJust());
-
-    bool r = deno::ExecuteV8StringSource(context, js_filename, source);
-    CHECK(r);
-
     if (source_map != nullptr) {
       v8::TryCatch try_catch(isolate);
       v8::ScriptOrigin origin(v8_str("set_source_map.js"));
@@ -551,6 +544,13 @@ void InitializeContext(v8::Isolate* isolate, v8::Local<v8::Context> context,
                       source_map_obj.ToLocalChecked())
                 .FromJust());
     }
+
+    auto source = deno::v8_str(js_source);
+    CHECK(
+        deno_val->Set(context, deno::v8_str("mainSource"), source).FromJust());
+
+    bool r = deno::ExecuteV8StringSource(context, js_filename, source);
+    CHECK(r);
   }
 }