The DOMSnapshot walk recursed one frame per nesting level. The MAX_NODES
cap bounds the node count but not the depth, so a deeply nested linear
chain (script can build thousands of nested elements) could overflow the
stack before the count guard triggered. Rewrite it with an explicit stack
so depth lives on the heap. Pre-order traversal and the MAX_NODES cap are
preserved.
Fixes#341.
SGavrl
e7300c5df7