Fix cross language associative update

1. This addresses a language only bug where modifying a variable should trigger associative language blocks that depend on the variable. This fix does not affect the current use cases of Dynamo unless users attempt to do nested language blocks in codeblock nodes that trigger cross language update.
Below is a simple case:

// Simplest case
a = 1;
x = [Associative]
{
    return = a + 100;
}
a = 2; //-> trigger update of inner block

2. This fix is also required by the local CBN implementation. Where CBN's will be compiled to language blocks.

@ke-yu , @lukechurch