Added language spelling out static type of prefix objects

docs/language/dartLangSpec.tex

 \documentclass{article}
 \usepackage{epsfig}
 \usepackage{color}
 \usepackage{dart}
 \usepackage{bnf}
 \usepackage{hyperref}
 \usepackage{lmodern}
 \newcommand{\code}[1]{{\sf #1}}
 \title{Dart Programming Language  Specification \\
 {\large Version 1.10}}
@@ skipping 6616 matching lines @@
 \item For every top level getter $g$ named $id$ in $B$, a corresponding getter named $id$ with the same signature as $g$.  Calling the method results in a runtime error.
 \item For every top level setter $s$ named $id$ in $B$, a corresponding setter named $id$ with the same signature as $s$.  Calling the method results in a runtime error.
 \item For every type $T$ named $id$ in $B$, a corresponding getter named $id$ with return type \code{Type}.  Calling the method results in a runtime error.
 \end{itemize}
 
 \rationale {
 The purpose of adding members of $B$ to $p$ is to ensure that any warnings  issued when using $p$ are correct, and no spurious warnings are generated.  In fact, at runtime we cannot add these members until $B$ is loaded; but any such invocations will fail at runtime as specified by virtue of being completely absent.
 }
 %But this is still a lie detectable by reflection. Probably revise so the type of p has these members but p does not.
 
+The static type of the prefix object $p$ is a unique interface type that has those members whose names and signatures are listed above.
+
 \LMHash{}
 After a call succeeds, the name $p$ is mapped to a non-deferred prefix object as described below. In addition, the prefix object also supports the \code{loadLibrary} method, and so it is possible to call \code{loadLibrary} again. If a call fails, nothing happens, and one again has the option to call \code{loadLibrary} again. Whether a repeated call to \code{loadLibrary} succeeds will vary as described below.
 
 \LMHash{}
 The effect of a repeated call to \code{$p$.loadLibrary} is as follows:
 \begin{itemize}
 \item
 If another call to \code{$p$.loadLibrary} has already succeeded, the repeated call also succeeds. 
 Otherwise,
 \item
@@ skipping 33 matching lines @@
 then let $NS_i = \SHOW{}([id_1, \ldots, id_k], NS_{i-1}$)
 
 where $show(l,n)$ takes a list of identifiers $l$ and a namespace $n$, and produces a namespace that maps each name in $l$ to the same element that $n$ does. Furthermore, for each name $x$ in $l$, if $n$ defines the name  $x=$ then the new namespace maps $x=$ to the same element that $n$ does. Otherwise the resulting mapping is undefined.
   
 \item If $C_i$ is of the form 
 
 \code{\HIDE{} $id_1, \ldots, id_k$} 
 
 then let $NS_i = \HIDE{}([id_1, \ldots, id_k], NS_{i-1}$) 
 
-where $hide(l, n)$ takes a list of identfiers $l$ and a namespace $n$, and produces a namespace that is identical to $n$ except that for each name $k$ in $l$, $k$ and $k=$ are undefined. 
+where $hide(l, n)$ takes a list of identifiers $l$ and a namespace $n$, and produces a namespace that is identical to $n$ except that for each name $k$ in $l$, $k$ and $k=$ are undefined. 
 \end{itemize}
  
 \LMHash{}
 Next, if $I$ includes a prefix clause of the form \AS{} $p$, let $NS =  NS_n \cup \{p: prefixObject(NS_n)\}$ where $prefixObject(NS_n)$ is a {\em prefix object} for the namespace $NS_n$, which is an object that has the following members:
 
 \begin{itemize}
 \item  For every top level function $f$ named $id$ in $NS_n$, a corresponding method with the same name and signature as $f$ that forwards  (\ref{functionDeclarations}) to $f$.
 \item For every top level getter  with the same name and signature as $g$ named $id$ in $NS_n$, a corresponding getter  that forwards to $g$.
 \item For every top level setter $s$  with the same name and signature as named $id$ in $NS_n$, a corresponding setter  that forwards to  $s$.
 \item For every type $T$ named $id$ in $NS_n$, a corresponding getter named $id$ with return type \code{Type}, that, when invoked, returns the type object for $T$.
 \end{itemize}
 
 \LMHash{}
 Otherwise, let $NS = NS_n$.
 It is a compile-time error if the current library declares a top-level member named $p$.
 
+The static type of the prefix object $p$ is a unique interface type that has those members whose names and signatures are listed above.
+% What is the static type of a prefix object. Need to state that is a(n anonymous) type that has members with the same names as signatures as above.
+
 % This is problematic, because it implies that p.T would be available even in a scope that declared p. We really need to think of p as a single object with properties p.T etc., except it isn't really that
 % either. After all, p isn't actually available as a stand alone name.
 
 \LMHash{}
 Then, for each entry mapping key $k$ to declaration $d$ in $NS$,  $d$ is made available in the top level scope of $L$ under the name $k$ unless either:
 \begin{itemize}
 \item
 a top-level declaration with the name $k$ exists in $L$, OR
 \item a prefix clause of the form  \AS{} $k$ is used in $L$.
 \end{itemize}
@@ skipping 1119 matching lines @@
 
 The invariant that each normative paragraph is associated with a line
 containing the text \LMHash{} should be maintained.  Extra occurrences
 of \LMHash{} can be added if needed, e.g., in order to make
 individual \item{}s in itemized lists addressable.  Each \LM.. command
 must occur on a separate line.  \LMHash{} must occur immediately
 before the associated paragraph, and \LMLabel must occur immediately
 after the associated \section{}, \subsection{} etc.
 
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