[debug] [reland] Consistently use script from FrameMirror

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 c7df61f3f49550bbc2087a9658a74e4e3af29661..87ebe44a4bb83f027c60e202e60b2cc5f426a9c5 100644
--- a/src/inspector/debugger_script_externs.js
+++ b/src/inspector/debugger_script_externs.js
@@ -44,7 +44,7 @@ var FormattedScript;
 var JavaScriptCallFrameDetails;
 
 /** @typedef {{
-        sourceID: function():(number|undefined),
+        sourceID: function():(number),
         line: function():number,
         column: function():number,
         thisObject: !Object,
@@ -288,6 +288,9 @@ FrameDetails.prototype.receiver = function() {}
 /** @return {function()} */
 FrameDetails.prototype.func = function() {}
 
+/** @return {!Object} */
+FrameDetails.prototype.script = function() {}
+
 /** @return {boolean} */
 FrameDetails.prototype.isAtReturn = function() {}
 
@@ -466,6 +469,9 @@ FrameMirror.prototype.allScopes = function(ignoreNestedScopes) {}
 /** @return {!FrameDetails} */
 FrameMirror.prototype.details = function() {}
 
+/** @return {!ScriptMirror} */
+FrameMirror.prototype.script = function() {}
+
 /**
  * @param {string} source
  * @param {boolean} disableBreak