attempt some fixes to failing tests (DOES NOT WORK)

[runningskull]

Before this patch, tests failed with these errors:

test/action.ts(265,25): error TS2339: Property 'x' does not exist on type '{}'.
test/hooks.ts(245,25): error TS2339: Property 'x' does not exist on type '{}'.
test/optimizations.ts(28,24): error TS2339: Property 'a' does not exist on type '{}'.
test/optimizations.ts(29,41): error TS2339: Property 'a' does not exist on type '{}'.
test/primitives.ts(49,29): error TS2339: Property 'date' does not exist on type '{}'.

After this patch, tests fail with these errors:

test/action.ts(265,45): error TS2339: Property 'x' does not exist on type 'IModelType<Snapshot<{ x: any; }>, { x: any; } & { inc: () => {}; }>'.
test/hooks.ts(245,41): error TS2339: Property 'x' does not exist on type 'IModelType<Snapshot<{ x: any; }>, { x: any; } & { postProcessSnapshot(s: any): any; } & { postPro...'.
test/optimizations.ts(28,24): error TS2339: Property 'a' does not exist on type 'IModelType<Snapshot<{ a: any; b: any; }>, { a: any; b: any; }>'.
test/optimizations.ts(29,61): error TS2339: Property 'a' does not exist on type 'IModelType<Snapshot<{ a: any; b: any; }>, { a: any; b: any; }>'.
test/primitives.ts(49,51): error TS2339: Property 'date' does not exist on type 'IModelType<Snapshot<{ date: any; }>, { date: any; }>'.