[debugger] remove mirror cache and v8::Debug::GetMirror.

src/inspector/debugger_script_externs.js

Index: src/inspector/debugger_script_externs.js
diff --git a/src/inspector/debugger_script_externs.js b/src/inspector/debugger_script_externs.js
index e2006309c4b214849ad73ed55900f837649d2e1a..478cd11f3be7f7837dc2c266142da4949d947429 100644
--- a/src/inspector/debugger_script_externs.js
+++ b/src/inspector/debugger_script_externs.js
@@ -238,16 +238,11 @@ FrameDetails.prototype.returnValue = function() {}
 /** @return {number} */
 FrameDetails.prototype.scopeCount = function() {}
 
-
-/** @param {boolean} value */
-function ToggleMirrorCache(value) {}
-
 /**
  * @param {*} value
- * @param {boolean=} transient
  * @return {!Mirror}
  */
-function MakeMirror(value, transient) {}
+function MakeMirror(value) {}
 
 
 /** @interface */