docs(*): Document a lot more symbols that are missing comments in our generated docs.

modules/angular2/src/facade/collection.ts

@@ -166,6 +166,10 @@ export class StringMapWrapper {
   }
 }
 
+/**
+ * A boolean-valued function over a value, possibly including context information
+ * regarding that value's position in an array.
+ */
 export interface Predicate<T> { (value: T, index?: number, array?: T[]): boolean; }
 
 export class ListWrapper {

modules/angular2/src/facade/exceptions.ts

@@ -12,6 +12,9 @@ export class BaseException extends Error {
   toString(): string { return this.message; }
 }
 
+/**
+ * Wraps an exception and provides additional context or information.
+ */
 export class WrappedException extends Error {
   private _wrapperStack: any;
 

modules/angular2/src/facade/lang.ts

@@ -29,6 +29,10 @@ export var Type = Function;
  * the `MyCustomComponent` constructor function.
  */
 export interface Type extends Function {}
+
+/**
+ * Runtime representation of a type that is constructable (non-abstract).
+ */
 export interface ConcreteType extends Type { new (...args): any; }
 
 export function getTypeNameForDebugging(type: Type): string {