Constrain _RenderScaledInlineWidget child size in computeDryLayout

[tgucio]

This PR constrains child size in _RenderScaledInlineWidget.computeDryLayout.

I found by accident that the test added in #130648 didn't really work i.e. didn't fail when reverting the change when run locally. It did fail with the values from #130588. Then this also showed the additional failing assertion:

00:01 +8: Inline widgets' scaled sizes are constrained                                                                                                                                                        
══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
The following assertion was thrown during performLayout():
The size given to the _RenderScaledInlineWidget class differs from the size computed by
computeDryLayout.
The size computed in performLayout is Size(502.5, 0.0), which is different from Size(502.5, 0.0),
which was computed by computeDryLayout.
The constraints used were BoxConstraints(0.0<=w<=502.5, 0.0<=h<=Infinity).
If you are not writing your own RenderBox subclass, then this is not
your fault. Contact support: https://github.com/flutter/flutter/issues/new?template=2_bug.yml

When the exception was thrown, this was the stack:
#0      RenderBox.debugAssertDoesMeetConstraints.<anonymous closure> (package:flutter/src/rendering/box.dart:2329:11)
#1      RenderBox.debugAssertDoesMeetConstraints (package:flutter/src/rendering/box.dart:2346:6)
#2      RenderBox.size=.<anonymous closure> (package:flutter/src/rendering/box.dart:2030:7)
#3      RenderBox.size= (package:flutter/src/rendering/box.dart:2032:6)
#4      _RenderScaledInlineWidget.performLayout (package:flutter/src/widgets/widget_span.dart:401:5)
#5      RenderObject.layout (package:flutter/src/rendering/object.dart:2548:7)
#6      RenderBox.layout (package:flutter/src/rendering/box.dart:2382:11)
#7      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:21)
#8      RenderObject.layout (package:flutter/src/rendering/object.dart:2548:7)
#9      RenderBox.layout (package:flutter/src/rendering/box.dart:2382:11)
#10     ChildLayoutHelper.layoutChild (package:flutter/src/rendering/layout_helper.dart:52:11)
#11     RenderInlineChildrenContainerDefaults._layoutChild (package:flutter/src/rendering/paragraph.dart:124:28)
#12     RenderInlineChildrenContainerDefaults.layoutInlineChildren (package:flutter/src/rendering/paragraph.dart:155:9)

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.

[LongCatIsLooong]

LGTM.

[LongCatIsLooong]

Ah I think I meant to put 100 here.