[inspector] always include user scripts in the snapshot.

test/inspector/debugger/step-snapshot-expected.txt

+Embedding script 'function c(f, ...args) { return f(...args); }'
+paused
+  }
+  #debugger;
+  c(f, 2);
+
+paused
+  debugger;
+  #c(f, 2);
+}
+
+paused
+function c(f, ...args) { #return f(...args); }
+
+paused
+  function f(x) {
+    #return x * 2;
+  }
+
+paused
+    return x * 2;
+  #}
+  debugger;
+
+paused
+function c(f, ...args) { return f(...args); #}
+
+paused
+  c(f, 2);
+#}
+
+paused
+test(#)