[inspector] De-flake inspector/debugger/get-possible-breakpoints.js.

Since the inspector does not longer hold on strongly to Script objects
after they were collected by V8, this test was relying on the GC to not
collect the scripts too eagerly in case where nothing else holds on to
the script. So explicitly adding a global object property assignment
here in those cases to ensure that the Script is kept alive.

Fixed: chromium:1314212, v8:12699
Bug: chromium:1246884, chromium:1295659
Change-Id: Ia16fcf841aeb29bf131fc6fa066f120d342f94b2
Doc: https://bit.ly/v8-inspector-script-caching
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3576117
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79852}

test/inspector/debugger/get-possible-breakpoints-expected.txt

@@ -273,12 +273,12 @@ function foo() { function boo() { #return 239# }; #boo #}
 #
 function foo() { let boo = #function() { #return 239# }; #}
 #
-#() => { #239 #}
+var foo = #() => { #239 #}
 #
 function foo() { #239 #}
 #
-#() => #239#
-#() => { #return 239# }#
+var foo = #() => #239#
+var foo = #() => { #return 239# }#
 
 Running test: argumentsAsCalls
 function foo(){#}

test/inspector/debugger/get-possible-breakpoints.js

@@ -137,11 +137,11 @@ function foo6() { Promise.resolve().then(() => 42) }
       .then(() => checkSource('function foo() { function boo() { return 239 }  }\n', { lineNumber: 0, columnNumber: 0 }))
       .then(() => checkSource('function foo() { function boo() { return 239 }; boo }\n', { lineNumber: 0, columnNumber: 0 }))
       .then(() => checkSource('function foo() { let boo = function() { return 239 }; }\n', { lineNumber: 0, columnNumber: 0 }))
-      .then(() => checkSource('() => { 239 }\n', { lineNumber: 0, columnNumber: 0 }))
+      .then(() => checkSource('var foo = () => { 239 }\n', { lineNumber: 0, columnNumber: 0 }))
       .then(() => checkSource('function foo() { 239 }\n', { lineNumber: 0, columnNumber: 0 }))
       // TODO(kozyatinskiy): lineNumber for return position should be only 9, not 8.
-      .then(() => checkSource('() => 239', { lineNumber: 0, columnNumber: 0 }))
-      .then(() => checkSource('() => { return 239 }', { lineNumber: 0, columnNumber: 0 }))
+      .then(() => checkSource('var foo = () => 239', { lineNumber: 0, columnNumber: 0 }))
+      .then(() => checkSource('var foo = () => { return 239 }', { lineNumber: 0, columnNumber: 0 }))
       .then(next);
   },