Minor cleanup in getDynamicIndentation

[ghost]

• getEffectiveDelta doesn't need a delta parameter, since that's in scope. Renaming this to getDelta since that's the property name.
• Break shouldAddDelta out of getIndentationForToken to clarify that there are only two possible return values. Moved the decorator check to the back (OK because all of the above code would return false;, so when we test this doesn't affect the result).