[lworld] C1 should avoid allocation when reading a field from a flattened field

When C1 compiles the following code

    inline class Point {int x, ..... }
    class Holder { Point point; }

    int x = holder.point.x

it first allocates a temporary Point object, copy the value of holder.point.x to the temp object, and then read x from the temp object. This should be simplified into a single load instruction

    x = ((int*)(holder))[offset of point.x];