refactor($parse): don't use bind-once interceptor for non-bind-once expressions

Side-effects:
  - Logic for allOrNothing watches now lives in $intercept rather than $parse

Credit to @jbedard for idea to remove $watch interceptors craziness from $interpolate.

Closes angular#9958

Author: caitp

src/ng/interpolate.js

@@ -202,7 +202,7 @@ function $InterpolateProvider() {
           }
           exp = text.substring(startIndex + startSymbolLength, endIndex);
           expressions.push(exp);
-          parseFns.push($parse(exp, parseStringifyInterceptor));
+          parseFns.push($parse(exp));
           index = endIndex + endSymbolLength;
           expressionPositions.push(concat.length);
           concat.push('');
@@ -232,7 +232,7 @@ function $InterpolateProvider() {
         var compute = function(values) {
           for (var i = 0, ii = expressions.length; i < ii; i++) {
             if (allOrNothing && isUndefined(values[i])) return;
-            concat[expressionPositions[i]] = values[i];
+            concat[expressionPositions[i]] = parseStringifyValue(values[i]);
           }
           return concat.join('');
         };
@@ -273,7 +273,7 @@ function $InterpolateProvider() {
               return compute(values);
             } catch (err) {
               var newErr = $interpolateMinErr('interr', "Can't interpolate: {0}\n{1}", text,
-                  err.toString());
+                err.toString());
               $exceptionHandler(newErr);
             }
 
@@ -299,12 +299,12 @@ function $InterpolateProvider() {
           replace(escapedEndRegexp, endSymbol);
       }
 
-      function parseStringifyInterceptor(value) {
+      function parseStringifyValue(value) {
         try {
           return stringify(getValue(value));
         } catch (err) {
           var newErr = $interpolateMinErr('interr', "Can't interpolate: {0}\n{1}", text,
-            err.toString());
+              err.toString());
           $exceptionHandler(newErr);
         }
       }

src/ng/parse.js

@@ -1253,13 +1253,22 @@ function $ParseProvider() {
 
     function addInterceptor(parsedExpression, interceptorFn) {
       if (!interceptorFn) return parsedExpression;
+      var watchDelegate = parsedExpression.$$watchDelegate;
 
-      var fn = function interceptedExpression(scope, locals) {
+      var regularWatch =
+          watchDelegate !== oneTimeLiteralWatchDelegate &&
+          watchDelegate !== oneTimeWatchDelegate;
+
+      var fn = regularWatch ? function regularInterceptedExpression(scope, locals) {
+        var value = parsedExpression(scope, locals);
+        var result = interceptorFn(value, scope, locals);
+        return result;
+      } : function oneTimeInterceptedExpression(scope, locals) {
         var value = parsedExpression(scope, locals);
         var result = interceptorFn(value, scope, locals);
         // we only return the interceptor's result if the
         // initial value is defined (for bind-once)
-        return isDefined(value) || interceptorFn.$stateful ? result : value;
+        return isDefined(value) ? result : value;
       };
 
       // Propagate $$watchDelegates other then inputsWatchDelegate