Bug 1263862 - Fix OOM case in ScopeIter::settle. r=jandem

js/src/jit-test/tests/gc/bug-1263862.js

@@ -0,0 +1,6 @@
+function loadFile(lfVarx) {
+  oomTest(() => eval(lfVarx));
+}
+for (var i = 0; i < 10; ++i) {
+  loadFile(`"use strict"; const s = () => s;`);
+}

js/src/vm/ScopeObject.cpp

@@ -1459,8 +1459,8 @@ ScopeIter::settle()
         // function frame case above, if the script starts with a lexical
         // block, the SSI could see 2 block scopes here. So skip between 1-2
         // static block scopes here.
-        MOZ_ASSERT(ssi_.type() == StaticScopeIter<CanGC>::Block);
-        incrementStaticScopeIter();
+        if (ssi_.type() == StaticScopeIter<CanGC>::Block)
+            incrementStaticScopeIter();
         if (ssi_.type() == StaticScopeIter<CanGC>::Block)
             incrementStaticScopeIter();
         MOZ_ASSERT(ssi_.type() == StaticScopeIter<CanGC>::Eval);