SetCanExecuteJavascriptOnMainFrame was only being set when there was a RenderProcessMessageHandler assigned, change so it's always set

Improve the formatting of the exception thrown

Author: amaitland

CefSharp.Core/Internals/ClientAdapter.cpp

@@ -1083,6 +1083,8 @@ namespace CefSharp
 
             if (name == kOnContextCreatedRequest)
             {
+                _browserControl->SetCanExecuteJavascriptOnMainFrame(true);
+
                 auto handler = _browserControl->RenderProcessMessageHandler;
 
                 if (handler != nullptr)
@@ -1091,14 +1093,14 @@ namespace CefSharp
                     CefFrameWrapper frameWrapper(browser->GetFrame(GetInt64(argList, 0)));
 
                     handler->OnContextCreated(_browserControl, browserWrapper, %frameWrapper);
-
-                    _browserControl->SetCanExecuteJavascriptOnMainFrame(true);
                 }
 
                 handled = true;
             }
             else if (name == kOnContextReleasedRequest)
             {
+                _browserControl->SetCanExecuteJavascriptOnMainFrame(false);
+
                 auto handler = _browserControl->RenderProcessMessageHandler;
 
                 if (handler != nullptr)
@@ -1107,8 +1109,6 @@ namespace CefSharp
                     CefFrameWrapper frameWrapper(browser->GetFrame(GetInt64(argList, 0)));
 
                     handler->OnContextReleased(_browserControl, browserWrapper, %frameWrapper);
-
-                    _browserControl->SetCanExecuteJavascriptOnMainFrame(false);
                 }
 
                 handled = true;

CefSharp/WebBrowserExtensions.cs

@@ -209,10 +209,10 @@ public static void ExecuteScriptAsync(this IWebBrowser browser, string script)
         {
             if (browser.CanExecuteJavascriptInMainFrame == false)
             {
-                throw new Exception(@"Unable to execute javascript at this time, scripts can only be executed within a V8Context.
-                                    Use the IWebBrowser.CanExecuteJavascriptInMainFrame property to guard against this exception.
-                                    See https://github.com/cefsharp/CefSharp/wiki/General-Usage#when-can-i-start-executing-javascript
-                                    for more details on when you can execute javascript.");
+                throw new Exception("Unable to execute javascript at this time, scripts can only be executed within a V8Context." +
+                                    "Use the IWebBrowser.CanExecuteJavascriptInMainFrame property to guard against this exception." +
+                                    "See https://github.com/cefsharp/CefSharp/wiki/General-Usage#when-can-i-start-executing-javascript " +
+                                    "for more details on when you can execute javascript.");
             }
 
             using (var frame = browser.GetMainFrame())
@@ -736,10 +736,10 @@ public static Task<JavascriptResponse> EvaluateScriptAsync(this IWebBrowser brow
 
             if(browser.CanExecuteJavascriptInMainFrame == false)
             {
-                throw new Exception(@"Unable to execute javascript at this time, scripts can only be executed within a V8Context.
-                                    Use the IWebBrowser.CanExecuteJavascriptInMainFrame property to guard against this exception.
-                                    See https://github.com/cefsharp/CefSharp/wiki/General-Usage#when-can-i-start-executing-javascript
-                                    for more details on when you can execute javascript.");
+                throw new Exception("Unable to execute javascript at this time, scripts can only be executed within a V8Context." +
+                                    "Use the IWebBrowser.CanExecuteJavascriptInMainFrame property to guard against this exception." +
+                                    "See https://github.com/cefsharp/CefSharp/wiki/General-Usage#when-can-i-start-executing-javascript " +
+                                    "for more details on when you can execute javascript.");
             }
 
             using (var frame = browser.GetMainFrame())