Introduce StackTraceOnThrowMixin.

sdk/lib/core/errors.dart

Index: sdk/lib/core/errors.dart
diff --git a/sdk/lib/core/errors.dart b/sdk/lib/core/errors.dart
index f61cdfe07f815bcdc596f8851d782cd77d486edc..6f01ce0c5de1d447c422631515e85a8ee1012fca 100644
--- a/sdk/lib/core/errors.dart
+++ b/sdk/lib/core/errors.dart
@@ -5,6 +5,8 @@
 part of dart.core;
 
 class Error {
+  const Error();
+
   /**
    * Safely convert a value to a [String] description.
    *
@@ -31,13 +33,33 @@ class Error {
 
   external static String _objectToString(Object object);
 
+  /**
+   * The stack trace of `this` error. May be null.
+   */
+  StackTrace get stackTrace => null;
+}
+
+/**
+ * Captures the stack trace when thrown.
+ */
+class StackTraceOnThrow {
+  /**
+   * Captures the current stack-trace when thrown.
+   *
+   * Classes extending or mixing-in this class will automatically have a stack
+   * trace captured the first time they are thrown. This stack trace is returned
+   * by the [stackTrace] getter.
+   *
+   * Throwing the object again will not cause overwrite the first stack trace,
+   * so bjects that are `StackTraceOnThrow` instances should not be reused.
+   */
   external StackTrace get stackTrace;
 }
 
 /**
  * Error thrown by the runtime system when an assert statement fails.
  */
-class AssertionError extends Error {
+class AssertionError extends Error with StackTraceOnThrow {
 }
 
 /**
@@ -49,13 +71,13 @@ class TypeError extends AssertionError {
 /**
  * Error thrown by the runtime system when a cast operation fails.
  */
-class CastError extends Error {
+class CastError extends Error with StackTraceOnThrow {
 }
 
 /**
  * Error thrown when attempting to throw [:null:].
  */
-class NullThrownError extends Error {
+class NullThrownError extends Error with StackTraceOnThrow {
   NullThrownError();
   String toString() => "Throw of null.";
 }
@@ -63,7 +85,7 @@ class NullThrownError extends Error {
 /**
  * Error thrown when a function is passed an unacceptable argument.
  */
-class ArgumentError extends Error {
+class ArgumentError extends Error with StackTraceOnThrow {
   final message;
 
   /** The [message] describes the erroneous argument. */
@@ -110,12 +132,12 @@ class RangeError extends ArgumentError {
  * of a switch) without meeting a break or similar end of the control
  * flow.
  */
-class FallThroughError extends Error {
-  FallThroughError();
+class FallThroughError extends Error with StackTraceOnThrow {
 }
 
 
-class AbstractClassInstantiationError extends Error {
+class AbstractClassInstantiationError
+    extends Error with StackTraceOnThrow {
   final String _className;
   AbstractClassInstantiationError(String this._className);
   String toString() => "Cannot instantiate abstract class: '$_className'";
@@ -124,7 +146,7 @@ class AbstractClassInstantiationError extends Error {
 /**
  * Error thrown by the default implementation of [:noSuchMethod:] on [Object].
  */
-class NoSuchMethodError extends Error {
+class NoSuchMethodError extends Error with StackTraceOnThrow {
   final Object _receiver;
   final String _memberName;
   final List _arguments;
@@ -162,7 +184,7 @@ class NoSuchMethodError extends Error {
  * This [Error] is thrown when an instance cannot implement one of the methods
  * in its signature.
  */
-class UnsupportedError extends Error {
+class UnsupportedError extends Error with StackTraceOnThrow {
   final String message;
   UnsupportedError(this.message);
   String toString() => "Unsupported operation: $message";
@@ -179,7 +201,8 @@ class UnsupportedError extends Error {
  * an [UnsupportedError] instead. This error is only intended for
  * use during development.
  */
-class UnimplementedError extends Error implements UnsupportedError {
+class UnimplementedError
+    extends Error with StackTraceOnThrow implements UnsupportedError {
   final String message;
   UnimplementedError([String this.message]);
   String toString() => (this.message != null
@@ -194,7 +217,7 @@ class UnimplementedError extends Error implements UnsupportedError {
  * This is a generic error used for a variety of different erroneous
  * actions. The message should be descriptive.
  */
-class StateError extends Error {
+class StateError extends Error with StackTraceOnThrow {
   final String message;
   StateError(this.message);
   String toString() => "Bad state: $message";
@@ -208,7 +231,7 @@ class StateError extends Error {
  * ([Iterable] or similar collection of values) should declare which operations
  * are allowed during an iteration.
  */
-class ConcurrentModificationError extends Error {
+class ConcurrentModificationError extends Error with StackTraceOnThrow {
   /** The object that was modified in an incompatible way. */
   final Object modifiedObject;
 
@@ -224,19 +247,15 @@ class ConcurrentModificationError extends Error {
 }
 
 
-class OutOfMemoryError implements Error {
+class OutOfMemoryError extends Error {
   const OutOfMemoryError();
   String toString() => "Out of Memory";
-
-  StackTrace get stackTrace => null;
 }
 
 
-class StackOverflowError implements Error {
+class StackOverflowError extends Error {
   const StackOverflowError();
   String toString() => "Stack Overflow";
-
-  StackTrace get stackTrace => null;
 }
 
 /**
@@ -246,7 +265,7 @@ class StackOverflowError implements Error {
  * the first time it is read. If evaluating the initializer expression causes
  * another read of the variable, this error is thrown.
  */
-class CyclicInitializationError extends Error {
+class CyclicInitializationError extends Error with StackTraceOnThrow {
   final String variableName;
   CyclicInitializationError([this.variableName]);
   String toString() => variableName == null