2.1.4 [ECMA-262/5] Section 12.15, The debugger statement
The specification states:
1. If an implementation defined debugging facility is available and enabled, then a. Perform an implementation defined debugging action. b. Let result be an implementation defined Completion value.
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If a debugger is attached to the currently executing program, step 1.a suspends execution and passes control to the debugger. If the debugger resumes execution of the program, step 1.b produces the Completion value of (