…displayed (javiereguiluz)

This PR was merged into the 2.7 branch.

Discussion
----------

Display a better error message when the toolbar cannot be displayed

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #23264
| License       | MIT
| Doc PR        | -

In action:

![profiler-error](https://user-images.githubusercontent.com/73419/27444352-5d0a1d60-5776-11e7-89c3-430cd6f38454.png)

Commits
-------

cc7275b Display a better error message when the toolbar cannot be displayed

…isplayed (yceruto)

This PR was squashed before being merged into the 2.7 branch (closes #23274).

Discussion
----------

Display a better error design when the toolbar cannot be displayed

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes (failure unrelated)
| Fixed tickets | #23266
| License       | MIT
| Doc PR        | n/a

Fixing the left position of the bar (tested in app without style) and escaping the literal newline (ES5) as some IDEs fails with previous syntax (and Github diff too). Btw, I have added the Symfony icon to make clear that this message comes from Symfony ;)

**Before:**
![current_toolbar_error](https://user-images.githubusercontent.com/2028198/27466735-cd5f0da8-57aa-11e7-8431-3025c41557e6.png)

**After:**
![after_toolbar_27](https://user-images.githubusercontent.com/2028198/27467928-75e45d4e-57b4-11e7-9e1f-e252d9085596.png)

Commits
-------

ed3e403 Display a better error design when the toolbar cannot be displayed