feat(jsruntime): js objects

[masnagam]

No description provided.

[masnagam]

hidden classes:

• Maps (Hidden Classes) in V8
• Hidden classes in JavaScript and Inline Caching

inline caching:

• Inline caching
• Inline caching - Max Bernstein
• Optimizing dynamic JavaScript with inline caches

[masnagam]

in the initial implementation, we focus on implementing operations defined in the specification and don't introduce any mechanisms to improve performance such as the inline caching.

we don't implement gc on this ticket. a separate ticket #237 has been created for that.

[masnagam]

in the first step, we implement the global environment specification type. currently, variables that are not defined in any lexical scopes causes panic!() in the jsruntime::semantics::scope.

we introduce a simple hashmap as a global object and move global variables such as print to the global object.