ECMA-262 specifies presence of "caller" and "arguments" properties on Function.prototype that each use the single realm-global %ThrowTypeError% as both getter and setter, and does not specify such properties on function instances (where their absence is arguably expected). But, as observed at endojs/endo#2655 (comment) , implementations diverge.

• JSC and SM follow spec by defining them only on Function.prototype (but violate it by having distinct values for the 4 respective getter/setter functions).
• V8 violates the spec by additionally defining them on Function() and non-strict function(){…} instances (non-writable and non-configurable null-valued data properties).
• XS violates the spec by additionally defining caller [although correctly omitting arguments] on Function() and non-strict function(){…} instances (writable and configurable undefined-valued data properties).
• Hermes violates the spec by omitting them from Function.prototype, and additionally by defining them on strict function(){…} instances (non-configurable accessor properties with %ThrowTypeError% getter/setter functions).

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And Hermes has an additional bug: in a module context, function(){} is treated differently from function(){ "use strict"; } (cf. Strict Mode Code, "Module code is always strict mode code") for both these function properties and for arguments.callee.