Fixed compilation error with inheritance of prototype interfaces

[sergeyklay]

Closes: #1758

[codecov]

Codecov Report

Merging #1770 into development will increase coverage by 0.44%.
The diff coverage is 25.92%.

@@                Coverage Diff                @@
##             development    #1770      +/-   ##
=================================================
+ Coverage          42.68%   43.12%   +0.44%     
- Complexity          8018     8019       +1     
=================================================
  Files                528      528              
  Lines              42049    42081      +32     
=================================================
+ Hits               17949    18149     +200     
+ Misses             24100    23932     -168

Impacted Files	Coverage Δ	Complexity Δ
Library/CompilerFile.php	64.2% <ø> (+3.11%)	154 <0> (ø)	⬇️
Library/ClassDefinition.php	46.84% <19.04%> (+17.99%)	271 <0> (+1)	⬆️
Library/Compiler.php	61.48% <50%> (+0.97%)	293 <0> (ø)	⬇️
Library/Backends/ZendEngine3/Backend.php	18.45% <0%> (+0.45%)	192% <0%> (ø)	⬇️
Library/ClassMethod.php	50.16% <0%> (+0.64%)	371% <0%> (ø)	⬇️
Library/CodePrinter.php	54.16% <0%> (+1.38%)	23% <0%> (ø)	⬇️
Library/functions.php	43.95% <0%> (+2.19%)	0% <0%> (ø)	⬇️
... and 2 more

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