Repository: flutter
Issue: Sometimes have to call `pod update` to resolve dependencies
Labels: tool,P2,team-tool,triaged-tool

## Steps to reproduce:
1) Add firebase_messaging as a dependency
1) `flutter run`, notice a need for firebase_core
1) add flrebase_core as a dependency
1) `flutter run`, notice build still fails

## Seen result:
`cd ios; pod update` fixes the build.

## Expected result:
I expect the flutter tool to handle that for me so I don't have to muck around with cocoapods

## Failure output:
```
$ flutter run
Launching lib/main.dart on iPhone (2) in debug mode...
Automatically signing iOS for device deployment using specified development team in Xcode project: <REDACTED>
Warning: CocoaPods recommended version 1.10.0 or greater not installed.
Pods handling may fail on some projects involving plugins.
To upgrade see https://guides.cocoapods.org/using/getting-started.html#installation for instructions.



Running pod install...                                           1,247ms
CocoaPods' output:
↳
      Preparing

    Analyzing dependencies

    Inspecting targets to integrate
      Using `ARCHS` setting to build architectures of target `Pods-Runner`: (``)

    Fetching external sources
    -> Fetching podspec for `Flutter` from `Flutter`
    -> Fetching podspec for `firebase_core` from `.symlinks/plugins/firebase_core/ios`
    firebase_core: Using Firebase SDK version '7.3.0' defined in 'firebase_core'
    -> Fetching podspec for `firebase_messaging` from `.symlinks/plugins/firebase_messaging/ios`
    firebase_messaging: Using Firebase SDK version '7.3.0' defined in 'firebase_core'

    Resolving dependencies of `Podfile`
      CDN: trunk Relative path: CocoaPods-version.yml exists! Returning local because checking is only perfomed in repo update
      CDN: trunk Relative path: all_pods_versions_0_3_5.txt exists! Returning local because checking is only perfomed in repo update
      CDN: trunk Relative path: Specs/0/3/5/Firebase/6.23.0/Firebase.podspec.json exists! Returning local because checking is only perfomed in repo update
    [!] CocoaPods could not find compatible versions for pod "Firebase/CoreOnly":
      In Podfile:
        firebase_core (from `.symlinks/plugins/firebase_core/ios`) was resolved to 1.0.1, which depends on
          Firebase/CoreOnly (= 7.3.0)

    None of your spec sources contain a spec satisfying the dependency: `Firebase/CoreOnly (= 7.3.0)`.

    You have either:
     * out-of-date source repos which you can update with `pod repo update` or with `pod install --repo-update`.
     * mistyped the name or version.
     * not added the source repo that hosts the Podspec to your Podfile.

    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:328:in `raise_error_unless_state'
    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:310:in `block in unwind_for_conflict'
    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:308:in `tap'
    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:308:in `unwind_for_conflict'
    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:257:in `process_topmost_state'
    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolution.rb:182:in `resolve'
    /Library/Ruby/Gems/2.6.0/gems/molinillo-0.6.6/lib/molinillo/resolver.rb:43:in `resolve'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/resolver.rb:94:in `resolve'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer/analyzer.rb:1065:in `block in resolve_dependencies'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/user_interface.rb:64:in `section'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer/analyzer.rb:1063:in `resolve_dependencies'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer/analyzer.rb:124:in `analyze'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer.rb:410:in `analyze'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer.rb:235:in `block in resolve_dependencies'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/user_interface.rb:64:in `section'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer.rb:234:in `resolve_dependencies'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/installer.rb:156:in `install!'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/command/install.rb:52:in `run'
    /Library/Ruby/Gems/2.6.0/gems/claide-1.0.3/lib/claide/command.rb:334:in `run'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/lib/cocoapods/command.rb:52:in `run'
    /Library/Ruby/Gems/2.6.0/gems/cocoapods-1.9.3/bin/pod:55:in `<top (required)>'
    /usr/local/bin/pod:23:in `load'
    /usr/local/bin/pod:23:in `<main>'

Error output from CocoaPods:
↳
    Ignoring ffi-1.12.2 because its extensions are not built. Try: gem pristine ffi --version 1.12.2

    [!] Automatically assigning platform `iOS` with version `10.0` on target `Runner` because no platform was specified. Please specify a platform for this target in your
    Podfile. See `https://guides.cocoapods.org/syntax/podfile.html#platform`.

Error: CocoaPods's specs repository is too out-of-date to satisfy dependencies.
To update the CocoaPods specs, run:
  pod repo update



Exception: Error running pod install
```