Bug 1552911 Comment 1 Edit History

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Original comment by
on 
In my debug build, we abort on the first line here, because `value` (of type `ResizeObserverSize*`) is null:
```c++
template <class T, GetOrCreateReflectorWrapBehavior wrapBehavior>
MOZ_ALWAYS_INLINE bool DoGetOrCreateDOMReflector(
    JSContext* cx, T* value, JS::Handle<JSObject*> givenProto,
    JS::MutableHandle<JS::Value> rval) {
  MOZ_ASSERT(value);
```
...because we're trying to read the `borderBoxSize` from a default-constructed `ResizeObserverEntry` object, and it's null.

(I assume that actual resizeobservers will produce `ResizeObserverEntry` objects with non-null `borderBoxSize` values, but in this case we're constructing one by hand from JS.)

In Chrome, the testcase throws `Uncaught TypeError: Illegal constructor` for the `new ResizeObserverEntry(o1)` JS.
Revision 1 by
on 
In my debug build, we abort on the first line here, because `value` (of type `ResizeObserverSize*`) is null:
```c++
template <class T, GetOrCreateReflectorWrapBehavior wrapBehavior>
MOZ_ALWAYS_INLINE bool DoGetOrCreateDOMReflector(
    JSContext* cx, T* value, JS::Handle<JSObject*> givenProto,
    JS::MutableHandle<JS::Value> rval) {
  MOZ_ASSERT(value);
```
...because we're trying to read the `borderBoxSize` from a default-constructed `ResizeObserverEntry` object, and it's null.

(I assume that actual resizeobservers will produce `ResizeObserverEntry` objects with non-null `borderBoxSize` values, but in this case we're constructing one by hand from JS, and it hasn't been given a borderBoxSize value.)

In Chrome, the testcase throws `Uncaught TypeError: Illegal constructor` for the `new ResizeObserverEntry(o1)` JS.

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